Probably, I've had mixed luck with it. Usually a call to the hotel works too, tell them you wont' stay for the second night if it's going to cost you more then two nights one at a time.

It's irritating that sometimes they will do a rate change so you save some bucks, and other times they won't and just hit you for some weird higher rate online for multi day reservations.

Or that they will display "as low as" and that's only for one night.