Don't make a mistake
I made a mistake and booked an extra day. The hotel indicated they were "glad" to shorten my reservation. They said "glad". Then later informed, only when I asked, that the hotel was going to bill me for the extra day. Of course they are glad! I would also be happy to be paid twice for the same room. In addition, the staff was rude when pressed on the issue.
I have stayed at this hotel before. Had planned to stay there in the future. Because of their poor customer service, I will not stay there again. They will lose much more than 1 day of revenue.