diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
index 07f7991..b5f4960 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
@@ -320,7 +320,7 @@ public function getTableMapping(array $storage_definitions = NULL) {
         if ($this->entityType->hasKey('revision_uuid')) {
           $revision_key_fields[] = $this->entityType->getKey('revision_uuid');
         }
-        $table_mapping->setFieldNames($this->revisionTable, array_merge($revision_key_fields, $revisionable_fields));
+        $table_mapping->setFieldNames($this->revisionTable, array_unique(array_merge($revision_key_fields, $revisionable_fields)));
       }
       elseif (!$revisionable && $translatable) {
         // Multilingual layouts store key field values in the base table. The
@@ -357,7 +357,7 @@ public function getTableMapping(array $storage_definitions = NULL) {
 
         $revision_data_key_fields = array($this->idKey, $this->revisionKey, $this->langcodeKey);
         $revision_data_fields = array_diff($revisionable_fields, $revision_metadata_fields, array($this->langcodeKey));
-        $table_mapping->setFieldNames($this->revisionDataTable, array_merge($revision_data_key_fields, $revision_data_fields));
+        $table_mapping->setFieldNames($this->revisionDataTable, array_unique(array_merge($revision_data_key_fields, $revision_data_fields)));
       }
 
       // Add dedicated tables.