Yes it is allowed. When you check the user list there are a lot of very similar user names on this forum. With the number of users on this forum filtering to disallow similar names would make it a chore to find a name that was not taken.
If that day ever comes when we have to ask 500 people or more to change user names because they are close to another one I will be taking a very long vacation.
That's too bad, espceially since Jolly Rancher is a rather uncommon name. But who knows- maybe you guys have the same name because you're so much alike and could be friends!