More can be added. I know that people have the right to create several accounts, but is it allowed to join different signature campaigns using alt account? or Appling using more than one account?
Users can control 1000 accounts if they want, as long as none are banned. You cannot join the same sig campaign that you already have an account in. I would also be bold enough to say that applying to the same sig campaign with multiple accounts should be forbidden, but not all managers may agree on that.