This is something we check during the registration (and rename) processes. Users cannot choose names that are already taken by someone else.
Also, users must not be able to use names which have been used by someone else in the past (deleted or renamed accounts)!
That's what this whole conversation is about. :) As I mentioned in me previous e-mail, we should store IDs and not names.
That also concerns the ACLs themselves, BTW, which means that the old- style way of editing ACLs on page with "ALLOW edit" must go away...
/Janne
