Actually, every time I do this at IHG (which I only do because of using a free night for part, and then paid stay or points for the rest), they give me bonus points for both check ins, which does surprise me. They list it as two reservations and stays on my account. I am not sure if that has changed. A couple recent yucky experience have caused me to use IHG less, but last time this was true, so I did not know that about Hilton. I think it's a fair question.