Are screen names unique?

I was wondering if the screen name you select when you first start the game is unique. i.e., if someone has taken "canadianhero" would I be forced to pick "canadianhero1" .

Thanks for the info

 

No they are not unique.

 

They are unique in conjuction with your charecter code. The three digits you see when hovering over your name.
So both yes and no.