Two Single Vanities Side By Side . Light gray bath vanities topped with white. We just moved into a condo built in the 70s and it has the original (laminate) 80 double vanity in our master bathroom. 23 Master Bathrooms With Two Vanities from www.homeepiphany.com They are using a common drain line that has a vent for a shower about 6 feet downline from the vanities. Add to that the additional cost of finishes and a larger vanity. Take into account your plumbing and other features in your room, as well as the bathroom door!