Question: Why does it say only rooms with single king beds are left?
The hotel is only allowed to commit to a set number of double bed rooms. Once that cap is reached, they can no longer guarantee the room.
But put your mind at ease....the hotel has LOTS of double bed rooms, and they assign them as people check in. If you're REALLY worried about guaranteeing a double bed room, then make sure you check in on January 25th rather than wait to check in on the 26th.