Very right, this is a good idea for people who wants to start the two but couldn't because of money. But let me tell you that some people just prefer to have just one instead of the two.
I understand that a single location is easier to manage, and it is also related to the demand of potential customers. So it can be one of both or the unisex, the area and the capital will determine the possibilities .How about a beauty and also a barbing saloon, it would be like killing two birds with one stone as that would generate profit from the two sides there in the area chosen.