If you own two resorts but the same UY and titled the same way, it will be one membership. Each can be used at 11 months at its own resort, but at 7 m thx you can combine the points from both to book. It really isn’t hard at all.
With a different UY, you are now talking two memberships. That means to use the points together, regardless of whether they are same resort, requires you to book whole nights on each and then link the reservations. Or transfer points from one to the other. But once transferred, you have to call MS to book as they won’t show up online.
So, keeping UY the same is ideal u less you have a specific reason not to. I have 3 UYs but since each has enough points in them..300, 350, and 150..I use them to book different trips and never combine as each can function on its own.