there has been a change in
joomla-cms/administrator/components/com_modules/tmpl/modules/default_batch_body.php
since joomla 3

It looks like it was an attempt to fix an issue whereby the language option didnt appear when a site had multiple admin languages installed but its not correct as it results in two language selectors when batch changing site modules.

From my tests the third instance of the language selector needs to be removed and that the problem is that this code is never evaluating as true and that is the real bug

$clientId == 1 && ModuleHelper::isAdminMultilang