The user can just ask the admins to change his or her name; or the admins will change the user's name. They did this to me when I picked the name, bitfighter, as my account name. I created another account and _k got angry and deleted the old account. They gave me the freedom of choice in what name to have though. I tried to find flaws in this game, too.
P.S. @ Lone wolf, I had the same profile picture for like a day, but got no trouble.
Also, just to prevent it 100%, the admins could block people from registering with the name, Chump Change. Two registered accounts cannot have the same name.