I did manage to get double stay credit once. I booked two rooms at a Hampton, with each room getting a separate folio under the door, with "A" and "B" after the res#. I asked that they be combined, which was done, however ... they put all the charges in "B", leaving "A" with a zero balance. The system picked up folio "A", giving me 1 stay and 4 nights, but no points whatsoever. The Diamond Desk rep added folio "B" as an overlapping stay with the correct points (and a 1/4 credit), keeping the original (1/4) posting for "A" in my account also.