there is no limitation as to the number of owners/users who can claim the exclusion
While possible, I just don't find it realistic that two families would live in a single family dwelling as their primary residence for two or more years. But if this is a duplex, then it's perfectly possible if each family lived in one of the units.
It's also possible for one family to live in it for two years, they move out and the other family moves in for 2 years. Then if it's sold before the 5-year mark of the first family moving in, both families would qualify. Of course, both families would also have a recapture and pay tax on their share of the recaptured depreciation too.
As a reminder to others, the 2 year count does not start until "after" your name is on the deed.
