<p>There are no restrictions at all on the uniqueness of user names, you're free to chose whatever name you wish. This is an intentional design decision. I personally find this rather nice, unlike many other sites an inactive user can't block your preferred user name.</p>

<p>There is a potential for confusion if two active users use the same name, but that is rather rare. There is the avatar to help distinguish users, and users can change their names in cases of true confusion.</p>

<p>The situation is not unlike the real world. Many people share the same name, but occasions where this gets problematic are still rather rare, and someone people tend to find an easy way to deal with it.</p>
