A few months back I booked a double room for my wife and myself at the Rome Mercure that I always use. At CI they told me that I had mistakenly booked a single room, so in case I was not satisfied with the double bed they had for me, I'd have to wait for a few hours till a bona fide room would be available. I took the one that was ready. At any rate, they told me that whatever I'd decide, the price would be the same with the exception of the Roman night tax that is calculated per person.