Changing back to previous name

Hello. I’m trying to help a friend who once had an ingamename, then changed it and now wants to change back. Apparently you can’t do that and it gives him a message saying something like “name in use” (I’m not sure what it says). Could this be a bug or is it possible to work it out via the admins?

Would be awesome if it was possible and if you want to get hold on me in chat my Xfire is “All3w”.

Ty, in advance
/All3