If you think there is a possibility that your two daughters will agree to share the bathroom for more than a year, MAYBE it is worth to have two sinks. Personally with a 5 ft vanity, I prefer one sink. You have more counter top and guests could appreciate that since they don't have drawers to put their stuff.

Definitely one sink. A duplicate sink is rarely used, but ample drawer space is always a plus.

I would go with a single. My DD has a 72" vanity with a knee space that she sits at to put on makeup (so she loses some drawer space) but she loves that she can spread out all of makeup, etc. If you think of two girls putting on makeup, etc in a five foot space, there's going to be elbows hitting each other so it may not really work.

Thanks for your thoughts. I’m going to start looking for 60in 1 sink vanities.

My DS just did this in her girls' bathroom. She offset the sink to one side further from the toilet (so it's not centered). This allowed more drawers and a large countertop area for all their beauty stuff. She changed the tub/shower combo to a shower, and put towels hooks instead of rods. She filled the whole width of the vanity with one large mirror.