diff -u b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php
--- b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php
+++ b/core/modules/menu_link_content/src/Plugin/migrate/source/d6/MenuLinkTranslation.php
@@ -47,10 +47,14 @@
    * {@inheritdoc}
    */
   public function prepareRow(Row $row) {
-    parent::prepareRow($row);
     $language = $row->getSourceProperty('language');
     $mlid = $row->getSourceProperty('mlid');
 
+    // If this row has been migrated it is a duplicate then skip it.
+    if ($this->idMap->lookupDestinationIds(['mlid' => $mlid, 'language' => $language])) {
+      return FALSE;
+    }
+
     // Save the translation for this property.
     $property = $row->getSourceProperty('property');
     $row->setSourceProperty($property . '_translated', $row->getSourceProperty('translation'));
@@ -67,6 +71,7 @@
     $query->addField('lt', 'translation');
     $results = $query->execute()->fetchAssoc();
     $row->setSourceProperty($other_property . '_translated', $results['translation']);
+    parent::prepareRow($row);
   }
 
   /**
diff -u b/core/modules/menu_link_content/tests/src/Kernel/Plugin/migrate/source/d6/MenuLinkTranslationTest.php b/core/modules/menu_link_content/tests/src/Kernel/Plugin/migrate/source/d6/MenuLinkTranslationTest.php
--- b/core/modules/menu_link_content/tests/src/Kernel/Plugin/migrate/source/d6/MenuLinkTranslationTest.php
+++ b/core/modules/menu_link_content/tests/src/Kernel/Plugin/migrate/source/d6/MenuLinkTranslationTest.php
@@ -211,7 +211,6 @@
         'description' => 'Test menu link 2',
         'title_translated' => 'fr - title translation',
         'description_translated' => 'fr - description translation',
-
       ],
       [
         'menu_name' => 'menu-test-menu',