Brion Vibber wrote in part:
We may wish to do a case-_in_sensitive check, and/or a
same-except-for-accents check. Or not. Anyway, I think it could use some
tidying up.
We'll probably never think of every way to mimic a previous user.
If there's an easy check to do (and there clearly are some),
then go ahead, but ultimately we'll need to rely on policy:
If somebody creates a username for fraudulent purposes
(as [[Fr:Utilisateur:Anthère]] was), then it should be removed
(as [[En:User:Throbbing Monster Cock]] was, for other reasons).
-- Toby