While importing https://commons.wikimedia.org/w/index.php?title=Template:Key_press/doc&action=history something went wrong: The last 10 revs were imported twice. Of course I tried to delete them (revdel). But this always looks like hiding something from the normal user and just creates curiosity. Therefore I deleted the whole page and attempted to restore only some of the revisions (the non-dupe ones). This didn't work. Even when selecting only one revision to undelete, the revision by the same user×tamp are undeleted.
Timestamp based revision deleting (evidence, HTML excerpt: <input type="checkbox" value="1" name="ts20111227115020">) and restoring should be banned from MediaWiki. This should work ID-based. This also for image-revision deleting/restoring.
Feel free to split or retarget this bug, as you like.