I checked doing a fake reservation, and although the system can do room shares and split the bill between two separate folios in the room, it doesn't seem to have the ability for there to be an Hhonors number added to the second folio for the room. I would go with the suggestion of two reservations and just make sure you call the hotel and let them know so they can assign you the same room ahead of time and you won't have to change rooms.