This question already has an answer here:
Someone went haywire a while back and upvoted practically all my questions in StackOverflow. This provided me with the daily cap of 200 rep and the mortarboard badge (for getting the daily max rep). After a few days, the system removed the gained reputation and upvotes from me, as it should've.
It didn't, however, take my mortarboard badge. Is this an intended feature, or something the devs have overlooked?