Does Hyatt have a general policy about the number of rooms that can be booked at a Senior rate ? I found a 13 year old post here that showed a Rate Rule that stated a limit of 1, but I'm not seeing that limit stated on the rates I'm looking at today. Every Marriott Senior rate I've looked at say there's a limit of 2 rooms per night, but Hyatt is silent ...
I don't think that "general policy" helps you much here. You really do need to look at the rate rules for the specific property. Last thing you need is to show up and have rooms above the allotted number, generally one, charged at the rack rate.