well it's a good idea because i know a friend have 8 accounts or 9 but at the same time it's a bad idea because what if i forgot my password or username and i didn't write anything at the email option? and i really did that and what if i'm not the only one who is using the PC? but maybe when someone press register while he is already have an account a window pop up and say why do you want to make a new account? and after he write his answer an admin can check it and the admin should accept or deny it