All names on each server are unique.
In order to have - as I do - Memphis Bill as a tank, and Memphis Bill as a Brute, they have to be on different servers. (Either that or use various capitalization tricks - like Memphis BiIl - or alter the name slightly.)
There's always the hyphen trick... Memphis-Bill. Or the pun route... Mephit Bill. 
I'm going to guess that the answer is "no", but I'm going to ask anyway.
Is it possible to have a villain with the same name as a hero?
(Reason I'm asking: I'm planning on re-rolling my main [Inv/SS tank] as an SS/Inv brute and then side-switching. Same name, same costume, etc. Am I gonna have to pay for a name change?)
"Everybody wants to change the world, but nobody wants to change themselves." -Tolstoy