Paying for the rooms in advance won't be a problem, just charge each card appropriately before your trip. I did have two rooms booked and they were under one reservation and one name. I was told that I could only put down one card for both rooms, since the rooms were booked under one reservation. I even asked for the manager and was told the same thing. I think since it's all under one name, they can't "break up" the reservation and the rooms are blocked the same. I think our room keys opened both doors too, if I remember correctly. If you want to have completely separate rooms, I'd break the reservation up into two separate reservations.