It would seem that we can name ourselves already existing toon names- I am talking with TWO people named Rage right now and imagine our surprise when they both ran across each other.
We should not be able to take someones exact name or we could suffer from impersonaters ripping people off or causing drama- For instance, I will be making a new toon named Victor sole to call people names and thus slander my poor friends in game name lolololol . =)