A different UY is a different membership. We have two--June and Dec--and so far, it hasn't been a problem.
However, we own 250 in one and 180 in the other so it allows us to use each one for different purposes. Having a small contract on its own would be a lot less convenient.
The one benefit to having both--which I did not think of when I did this--is that I now have points that cover the entire year so I am always traveling within a banking window.
One UY is certainly easier to manage and when booking at 7 months--if you you are getting a different resort--all points can be used for one seamless transition.
With two memberships, when booking online, you have to book part with one contract and part with the other and then ask for the reservations to be linked. The only other way is to call MS and do a transfer between the two before booking.
Unless you have a specific reason for getting a different UY, I'd stay with one. If you do decide to do it, make sure that you have thought of how it will work as its own membership.
Good luck!