I booked 2 rooms using my points for a category 4 hotel recently, during the booking , i specifically chose to use points instead of my 2 CAT5 certificate. After my stay, i found out that the marriot.com only charged me 20K points and used one of my CAT5 certificate. The bizarre part is that I got 3 confirmation letters :
1. the first email confirmed my booking with 20K X 2 rooms.
2. the second email confirmed that 40K points were credited back to me
3. the last email confirmed that one of my CAT5 certificate was USED for one of the room!!
Have you encountered the same issue? i called in today to marriott rewards help, but they could not explain this behavior, but they did admit that if you book 2 rooms in the single stay, there were some issues with the system. This is very frastrating as i need to call in to ask them to give me back my CAT5 certificate and use 20K points.