Hilton now consider an overlapping stay where you check out and in again on the same day/same hotel.

Say you have 2 weeks booked at a Hilton and check out on July 2nd then you find the airline cancels your flight so you need to have another 1 night stay in the same hotel.
You book it and check IN to the new booking on July 2nd.
You will not earn the previous 2 weeks HH points as it's classed as an overlap!