Are you talking about using a DSU at two properties?
Are you talking about using a guest of honor functionality through a points reservation?

I doubt the hotels are going to call each other so you would likely get the standard benefits at both hotels. You of course wont get stay/night credit at both. You would get lounge access for the guests at both hotels along with potential for upgrades (better view or whateveR) assuming you're just doing a standard diamond checkin.

Wellcome to FT.