Depends a great deal upon just why a given screen name was banned, I suppose. I do know that I’ve seen previously “banned” FReepers return, so it’s not technically impossible. Whether the account history, signup date, home page, etc. would remain, I couldn’t say.
I’ve seen at least two previously banned freepers get unbanned. One of them has been banned at least 3 times that I am aware of, yet he is still here posting as of yesterday. Why they were banned then allowed to return, I have no idea.
Speaking of which, what was libbylu’s full name, and is she still with us?