As you might know, dubble posting is considered spam and thus not allowed in RP. However, I have a new rule posted up about that fact:
Double posting is not allowed when in a RP area with at least one other character.
Double posting is allowed in case you are the ONLY person in a RP area and no one comes around to join you. This makes double posting allowed in case your character is in class or in another area waiting for the next change of time and you want to keep your character active throughout RP without having someone to respond to.
There we go. c: