diff --git a/CHANGELOG.md b/CHANGELOG.md
index 12436812ca..f8e1a1399c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 ### Added
 
 - Methods to get style for row or column. [PR #4317](https://github.com/PHPOffice/PhpSpreadsheet/pull/4317)
+- Method for duplicating worksheet in spreadsheet. [PR #4315](https://github.com/PHPOffice/PhpSpreadsheet/pull/4315)
 
 ### Changed
 
@@ -25,7 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 ### Fixed
 
-- Nothing yet.
+- Ods Reader Sheet Names with Period. [Issue #4311](https://github.com/PHPOffice/PhpSpreadsheet/issues/4311) [PR #4313](https://github.com/PHPOffice/PhpSpreadsheet/pull/4313)
 
 ## 2025-01-11 - 3.8.0
 
diff --git a/docs/topics/worksheets.md b/docs/topics/worksheets.md
index 0199f13c6a..5b15089b61 100644
--- a/docs/topics/worksheets.md
+++ b/docs/topics/worksheets.md
@@ -95,19 +95,38 @@ insert the clone into the workbook.
 
 ```php
 $clonedWorksheet = clone $spreadsheet->getSheetByName('Worksheet 1');
-$clonedWorksheet->setTitle('Copy of Worksheet 1');
+$clonedWorksheet->setTitle('Copy of Worksheet 1'); // must be unique
 $spreadsheet->addSheet($clonedWorksheet);
 ```
+Starting with PhpSpreadsheet 3.9.0, this can be done more simply (copied sheet's title will be set to something unique):
+```php
+$copiedWorksheet = $spreadsheet->duplicateWorksheetByTitle('sheetname');
+```
 
 You can also copy worksheets from one workbook to another, though this
 is more complex as PhpSpreadsheet also has to replicate the styling
 between the two workbooks. The `addExternalSheet()` method is provided for
 this purpose.
 
-    $clonedWorksheet = clone $spreadsheet1->getSheetByName('Worksheet 1');
-    $spreadsheet->addExternalSheet($clonedWorksheet);
+```php
+$clonedWorksheet = clone $spreadsheet1->getSheetByName('Worksheet 1');
+$clonedWorksheet->setTitle('Copy of Worksheet 1'); // must be unique
+$spreadsheet1->addSheet($clonedWorksheet);
+$spreadsheet->addExternalSheet($clonedWorksheet);
+```
+Starting with PhpSpreadsheet 3.8.0, this can be simplified:
+```php
+$clonedWorksheet = clone $spreadsheet1->getSheetByName('Worksheet 1');
+$spreadsheet1->addSheet($clonedWorksheet, null, true);
+$spreadsheet->addExternalSheet($clonedWorksheet);
+```
+Starting with PhpSpreadsheet 3.9.0, this can be simplified even further:
+```php
+$clonedWorksheet = $spreadsheet1->duplicateWorksheetByTitle('sheetname');
+$spreadsheet->addExternalSheet($clonedWorksheet);
+```
 
-In both cases, it is the developer's responsibility to ensure that
+In the cases commented "must be unique", it is the developer's responsibility to ensure that
 worksheet names are not duplicated. PhpSpreadsheet will throw an
 exception if you attempt to copy worksheets that will result in a
 duplicate name.
diff --git a/src/PhpSpreadsheet/Reader/Ods/FormulaTranslator.php b/src/PhpSpreadsheet/Reader/Ods/FormulaTranslator.php
index 27862d7a5a..6e54e0039e 100644
--- a/src/PhpSpreadsheet/Reader/Ods/FormulaTranslator.php
+++ b/src/PhpSpreadsheet/Reader/Ods/FormulaTranslator.php
@@ -6,10 +6,24 @@
 
 class FormulaTranslator
 {
-    public static function convertToExcelAddressValue(string $openOfficeAddress): string
+    private static function replaceQuotedPeriod(string $value): string
     {
-        $excelAddress = $openOfficeAddress;
+        $value2 = '';
+        $quoted = false;
+        foreach (mb_str_split($value, 1, 'UTF-8') as $char) {
+            if ($char === "'") {
+                $quoted = !$quoted;
+            } elseif ($char === '.' && $quoted) {
+                $char = "\u{fffe}";
+            }
+            $value2 .= $char;
+        }
 
+        return $value2;
+    }
+
+    public static function convertToExcelAddressValue(string $openOfficeAddress): string
+    {
         // Cell range 3-d reference
         // As we don't support 3-d ranges, we're just going to take a quick and dirty approach
         //  and assume that the second worksheet reference is the same as the first
@@ -20,6 +34,7 @@ public static function convertToExcelAddressValue(string $openOfficeAddress): st
                 '/\$?([^\.]+)\.([^\.]+)/miu', // Cell reference in another sheet
                 '/\.([^\.]+):\.([^\.]+)/miu', // Cell range reference
                 '/\.([^\.]+)/miu', // Simple cell reference
+                '/\\x{FFFE}/miu', // restore quoted periods
             ],
             [
                 '$1!$2:$4',
@@ -27,8 +42,9 @@ public static function convertToExcelAddressValue(string $openOfficeAddress): st
                 '$1!$2',
                 '$1:$2',
                 '$1',
+                '.',
             ],
-            $excelAddress
+            self::replaceQuotedPeriod($openOfficeAddress)
         );
 
         return $excelAddress;
@@ -52,14 +68,16 @@ public static function convertToExcelFormulaValue(string $openOfficeFormula): st
                         '/\[\$?([^\.]+)\.([^\.]+)\]/miu', // Cell reference in another sheet
                         '/\[\.([^\.]+):\.([^\.]+)\]/miu', // Cell range reference
                         '/\[\.([^\.]+)\]/miu', // Simple cell reference
+                        '/\\x{FFFE}/miu', // restore quoted periods
                     ],
                     [
                         '$1!$2:$3',
                         '$1!$2',
                         '$1:$2',
                         '$1',
+                        '.',
                     ],
-                    $value
+                    self::replaceQuotedPeriod($value)
                 );
                 // Convert references to defined names/formulae
                 $value = str_replace('$$', '', $value);
diff --git a/src/PhpSpreadsheet/Spreadsheet.php b/src/PhpSpreadsheet/Spreadsheet.php
index 650da9b68d..86f9d891ea 100644
--- a/src/PhpSpreadsheet/Spreadsheet.php
+++ b/src/PhpSpreadsheet/Spreadsheet.php
@@ -529,6 +529,15 @@ public function sheetNameExists(string $worksheetName): bool
         return $this->getSheetByName($worksheetName) !== null;
     }
 
+    public function duplicateWorksheetByTitle(string $title): Worksheet
+    {
+        $original = $this->getSheetByNameOrThrow($title);
+        $index = $this->getIndex($original) + 1;
+        $clone = clone $original;
+
+        return $this->addSheet($clone, $index, true);
+    }
+
     /**
      * Add sheet.
      *
diff --git a/tests/PhpSpreadsheetTests/Document/PropertiesTest.php b/tests/PhpSpreadsheetTests/Document/PropertiesTest.php
index 1b32aeaec9..dd8dabb21f 100644
--- a/tests/PhpSpreadsheetTests/Document/PropertiesTest.php
+++ b/tests/PhpSpreadsheetTests/Document/PropertiesTest.php
@@ -8,6 +8,7 @@
 use DateTimeZone;
 use PhpOffice\PhpSpreadsheet\Document\Properties;
 use PhpOffice\PhpSpreadsheet\Shared\Date;
+use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 
 class PropertiesTest extends TestCase
@@ -16,7 +17,7 @@ class PropertiesTest extends TestCase
 
     private float $startTime;
 
-    protected function setup(): void
+    protected function setUp(): void
     {
         do {
             // loop to avoid rare situation where timestamp changes
@@ -44,12 +45,19 @@ public function testSetCreator(): void
         self::assertSame($creator, $this->properties->getCreator());
     }
 
-    #[\PHPUnit\Framework\Attributes\DataProvider('providerCreationTime')]
+    #[DataProvider('providerCreationTime')]
     public function testSetCreated(null|int $expectedCreationTime, null|int|string $created): void
     {
-        $expectedCreationTime = $expectedCreationTime ?? $this->startTime;
-
-        $this->properties->setCreated($created);
+        if ($expectedCreationTime === null) {
+            do {
+                // loop to avoid rare situation where timestamp changes
+                $expectedCreationTime = (float) (new DateTime())->format('U');
+                $this->properties->setCreated($created);
+                $endTime = (float) (new DateTime())->format('U');
+            } while ($expectedCreationTime !== $endTime);
+        } else {
+            $this->properties->setCreated($created);
+        }
         self::assertEquals($expectedCreationTime, $this->properties->getCreated());
     }
 
@@ -71,12 +79,19 @@ public function testSetModifier(): void
         self::assertSame($creator, $this->properties->getLastModifiedBy());
     }
 
-    #[\PHPUnit\Framework\Attributes\DataProvider('providerModifiedTime')]
+    #[DataProvider('providerModifiedTime')]
     public function testSetModified(mixed $expectedModifiedTime, null|int|string $modified): void
     {
-        $expectedModifiedTime = $expectedModifiedTime ?? $this->startTime;
-
-        $this->properties->setModified($modified);
+        if ($expectedModifiedTime === null) {
+            do {
+                // loop to avoid rare situation where timestamp changes
+                $expectedModifiedTime = (float) (new DateTime())->format('U');
+                $this->properties->setModified($modified);
+                $endTime = (float) (new DateTime())->format('U');
+            } while ($expectedModifiedTime !== $endTime);
+        } else {
+            $this->properties->setModified($modified);
+        }
         self::assertEquals($expectedModifiedTime, $this->properties->getModified());
     }
 
@@ -146,7 +161,7 @@ public function testSetManager(): void
         self::assertSame($manager, $this->properties->getManager());
     }
 
-    #[\PHPUnit\Framework\Attributes\DataProvider('providerCustomProperties')]
+    #[DataProvider('providerCustomProperties')]
     public function testSetCustomProperties(mixed $expectedType, mixed $expectedValue, string $propertyName, null|bool|float|int|string $propertyValue, ?string $propertyType = null): void
     {
         if ($propertyType === null) {
diff --git a/tests/PhpSpreadsheetTests/Reader/Ods/FormulaTranslatorTest.php b/tests/PhpSpreadsheetTests/Reader/Ods/FormulaTranslatorTest.php
new file mode 100644
index 0000000000..8246784bf3
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Ods/FormulaTranslatorTest.php
@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Ods;
+
+use PhpOffice\PhpSpreadsheet\Reader\Ods\FormulaTranslator;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+class FormulaTranslatorTest extends TestCase
+{
+    #[DataProvider('addressesProvider')]
+    public function testAddresses(string $result, string $address): void
+    {
+        self::assertSame($result, FormulaTranslator::convertToExcelAddressValue($address));
+    }
+
+    public static function addressesProvider(): array
+    {
+        return [
+            'range period in sheet name' => ["'sheet1.bug'!a1:a5", "'sheet1.bug'.a1:'sheet1.bug'.a5"],
+            'range special chars and period in sheet name' => ["'#sheet1.x'!a1:a5", "'#sheet1.x'.a1:'#sheet1.x'.a5"],
+            'cell period in sheet name' => ["'sheet1.bug'!b9", "'sheet1.bug'.b9"],
+            'range unquoted sheet name' => ['sheet1!b9:c12', 'sheet1.b9:sheet1.c12'],
+            'range unquoted sheet name with $' => ['sheet1!$b9:c$12', 'sheet1.$b9:sheet1.c$12'],
+            'range quoted sheet name with $' => ["'sheet1'!\$b9:c\$12", '\'sheet1\'.$b9:\'sheet1\'.c$12'],
+            'cell unquoted sheet name' => ['sheet1!B$9', 'sheet1.B$9'],
+            'range no sheet name all dollars' => ['$B$9:$C$12', '$B$9:$C$12'],
+            'range no sheet name some dollars' => ['B$9:$C12', 'B$9:$C12'],
+            'range no sheet name no dollars' => ['B9:C12', 'B9:C12'],
+        ];
+    }
+
+    #[DataProvider('formulaProvider')]
+    public function testFormulas(string $result, string $formula): void
+    {
+        self::assertSame($result, FormulaTranslator::convertToExcelFormulaValue($formula));
+    }
+
+    public static function formulaProvider(): array
+    {
+        return [
+            'ranges no sheet name' => [
+                'SUM(A5:A7,B$5:$B7)',
+                'SUM([.A5:.A7];[.B$5:.$B7])',
+            ],
+            'ranges sheet name with period' => [
+                'SUM(\'test.bug\'!A5:A7,\'test.bug\'!B5:B7)',
+                'SUM([\'test.bug\'.A5:.A7];[\'test.bug\'.B5:.B7])',
+            ],
+            'ranges unquoted sheet name' => [
+                'SUM(testbug!A5:A7,testbug!B5:B7)',
+                'SUM([testbug.A5:.A7];[testbug.B5:.B7])',
+            ],
+            'ranges quoted sheet name without period' => [
+                'SUM(\'testbug\'!A5:A7,\'testbug\'!B5:B7)',
+                'SUM([\'testbug\'.A5:.A7];[\'testbug\'.B5:.B7])',
+            ],
+        ];
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/SpreadsheetDuplicateSheetTest.php b/tests/PhpSpreadsheetTests/SpreadsheetDuplicateSheetTest.php
new file mode 100644
index 0000000000..b84026700e
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/SpreadsheetDuplicateSheetTest.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests;
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PHPUnit\Framework\TestCase;
+
+class SpreadsheetDuplicateSheetTest extends TestCase
+{
+    private ?Spreadsheet $spreadsheet = null;
+
+    protected function tearDown(): void
+    {
+        if ($this->spreadsheet !== null) {
+            $this->spreadsheet->disconnectWorksheets();
+            $this->spreadsheet = null;
+        }
+    }
+
+    public function testDuplicate(): void
+    {
+        $this->spreadsheet = new Spreadsheet();
+        $sheet = $this->spreadsheet->getActiveSheet();
+        $sheet->setTitle('original');
+        $sheet->getCell('A1')->setValue('text1');
+        $sheet->getCell('A2')->setValue('text2');
+        $sheet->getStyle('A1')
+            ->getFont()
+            ->setBold(true);
+        $sheet3 = $this->spreadsheet->createSheet();
+        $sheet3->setTitle('added');
+        $newSheet = $this->spreadsheet
+            ->duplicateWorksheetByTitle('original');
+        $this->spreadsheet->duplicateWorksheetByTitle('added');
+        self::assertSame('original 1', $newSheet->getTitle());
+        self::assertSame(
+            'text1',
+            $newSheet->getCell('A1')->getValue()
+        );
+        self::assertSame(
+            'text2',
+            $newSheet->getCell('A2')->getValue()
+        );
+        self::assertTrue(
+            $newSheet->getStyle('A1')->getFont()->getBold()
+        );
+        self::assertFalse(
+            $newSheet->getStyle('A2')->getFont()->getBold()
+        );
+        $sheetNames = [];
+        foreach ($this->spreadsheet->getWorksheetIterator() as $worksheet) {
+            $sheetNames[] = $worksheet->getTitle();
+        }
+        $expected = ['original', 'original 1', 'added', 'added 1'];
+        self::assertSame($expected, $sheetNames);
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Writer/Ods/AutoFilterTest.php b/tests/PhpSpreadsheetTests/Writer/Ods/AutoFilterTest.php
index ddfe85570a..952db5cb5b 100644
--- a/tests/PhpSpreadsheetTests/Writer/Ods/AutoFilterTest.php
+++ b/tests/PhpSpreadsheetTests/Writer/Ods/AutoFilterTest.php
@@ -32,4 +32,29 @@ public function testAutoFilterWriter(): void
 
         self::assertSame('A1:C9', $reloaded->getActiveSheet()->getAutoFilter()->getRange());
     }
+
+    public function testPeriodInSheetNames(): void
+    {
+        $spreadsheet = new Spreadsheet();
+        $worksheet = $spreadsheet->getActiveSheet();
+        $worksheet->setTitle('work.sheet');
+
+        $dataSet = [
+            ['Year', 'Quarter', 'Sales'],
+            [2020, 'Q1', 100],
+            [2020, 'Q2', 120],
+            [2020, 'Q3', 140],
+            [2020, 'Q4', 160],
+            [2021, 'Q1', 180],
+            [2021, 'Q2', 75],
+            [2021, 'Q3', 0],
+            [2021, 'Q4', 0],
+        ];
+        $worksheet->fromArray($dataSet, null, 'A1');
+        $worksheet->getAutoFilter()->setRange('A1:C9');
+
+        $reloaded = $this->writeAndReload($spreadsheet, 'Ods');
+
+        self::assertSame('A1:C9', $reloaded->getActiveSheet()->getAutoFilter()->getRange());
+    }
 }