Manual:FixDoubleRedirects.php

Details
fixDoubleRedirects.php file is a maintenance script located in the maintenance directory that can be used to fix double redirects. The edits will be attributed to the user named in the MediaWiki:Double-redirect-fixer message (User:Redirect fixer on English wikis by default). Edits made by this script are not shown on Special:RecentChanges, but they do appear in that user's contribs. The edit summary comes from the MediaWiki:Double-redirect-fixed-maintenance message.

This script was introduced in MediaWiki 1.18 (r81408) and is written for that version. For a version that runs on older MediaWiki versions (tested on 1.16), see here.