Make display names unique

[MitMaro]

Display names need to be unique. Since we allow non-alpha numeric characters, uniqueness should be based on only an alphanumeric representation of the string.

[whymarrh]

Should we be worried about people changing their display name and having their old name used by another user?

We could keep a list of the display names used and not allow the use of a name that has been used at some point in the past. I'm just not sure if it's needed.

[MitMaro]

We currently have a database design that keeps a record of all past display names and do not allow someone to use an existing name, past or present.

It wouldn't hurt to only allow a set number of changes (I would think 2 additional changes, for 3 total names).