You can only receive one night credit each night regardless of the number of rooms you book at one hotel or multiple hotels. This has been the policy for as long as I can remember.
https://www.flyertalk.com/forum/hilt...e-rooms-2.html
Two concurrent stays same city
Two hotels booked same night same city - honors points question.
Two Reservations

You can always ask Hilton to make an exception or otherwise seek some consideration Hilton has been having with the stay counter counting non-qualifying nights.
Milestone Bonus
If Hilton's IT dept doesn't know, how am I supposed to?