Yes, I have!

Actually we have several clients that are spouses each wanting their own space, so it isn't only shared families that like the double master layout.

Hank, check out Lennar Builders new floor plan, called NextGen - I think this is going to be more and more popular with an aging population!  Lennar has done a great job with this design.

Like a Duplex, or are these not separated?

Yes.

Yes.

We have a few for sale - new construction. One suite is on the first floor, and the second above. It opens up more options for mixed families, guests, or for folks who might be thinking ahead to stairs being a burden during later years. 

Yes, though more often it's a home with an in-law suite or a guest home.

Spouses sometimes want their own space. Seniors many have the greatest need when one person is ill and needs nursing care.

In my area the older folks are selling and moving to where their kids are.

I have a number of clients that are looking for an additional first floor bedroom with bath for parents.  Usually, the couple prefers being on the same floor with their kids and having their parents on first floor, for ease and privacy.

We are seeing a return of the true mother in law plan. You take a 3 bed and 2 bath house with the beds and bath on one side, and you add another bed, bath, and small living on the other. This creates a suite set up as we go back to multi-generational living.

Two bedroom homes are very hard to sell in my area, 3 bedrooms being the norm.

However, builders offer two master town homes and they are usually sold to a person who wants to rent one and occupy the other. 

I have sold several homes with two owner's suites.  Some for parents, some for adult kids. 

We see them here in Florida, and families who are dealing with aging parents love them.  Typically one master on each floor; it is great!

I have seen some of these, but they aren't as common in my area.  It's very rare to see 2 siblings together, and way more common to have family + one side of parents.

I have sold these; I've been asked for these more than I can find supply of them. It will be a big trend in the years to come, I'm sure.

I currently have a listing with two master suites.