Advance booking at Hilton and Doubletree in NY

Hi all,

I will be in New York from 14-29 November and I booked rooms at Doubletree Jersey City, Hilton Niagara Falls and Hilton Time Square a month back. I noticed that I got charged once and not for all 3 hotels. Is it normal?

I also noticed that the price of the rooms got cheaper recently. Has anyone had the same issue before? Can we ask for the cheaper room rate? Will there be admin charges?