Since the release of Joomla 2.5 there has been a particularly annoying “duplicate template” bug that becomes clearly evident when you install or update a template. As our primary business involves templates, and as a result the vast majority of our users install templates, this has caused a great deal of confusion and consternation among our users.
This bug was identified and patched in the Joomla platform shortly after the 2.5.0 release, however, Joomla is currently at 2.5.2 at the time of this writing and this issue remains because the Joomla platfrom fix has not been merged into the Joomla CMS code. Even when this fix makes it into the Joomla CMS codebase, it will not fix the multiple duplicate database entries that result from the buggy template installer file.