There was a thread about this, but recently they've said it would be too difficult to do, so don't expect it anytime soon. They'll only change it if you have a really good reason to, you can email ferret@armorgames.com about it.
Um, I don't think you are able to create a new one, but no one would know if you created and new user... Not saying I've done it...! *tisk* No, for realzies, I haven't. But yes, it would be SUPER confusing.