Whenever we've had a Pin code, we've been able to book a maximum of 3 rooms for any particular vacation using the Pin -- and those three rooms could be at three different resorts if we wanted to do it that way (I once used my Pin code and booked for our group two rooms at GF and one room at CR as my sister likes CR better). I have not tried to book more than one room on-line, however, with a Pin code. I've been wondering myself how to do it. I think I would just call CRO to book it.
In my experience, we have had to put down a deposit for each room booked wih a Pin code. I don't recall if we had to have exactly the same dates in each room (I think the answer is no, but double-check on that).