Manual:NamespaceDupes.php

namespaceDupes.php is a maintenance script located in the maintenance directory that can be used to clean up inaccessible titles after adding a namespace (or interwiki prefix).

Usage
Go to the maintenance directory and run: php namespaceDupes.php --fix

Script specific parameters: --fix: Attempt to automatically fix errors --prefix: Do an explicit check for the given title prefix appended after the article name --suffix: Dupes will be renamed with correct namespace with appended after the article name