More than one wife is acceptable in many cultures; wouldn't it be easier if they were sisters.
Yes, it is indeed acceptable in many cultures (even in mine ) and I can understand that (although I couldn't be part of it).
I just don't see how being with 2 sisters would make it easier (some women should be off-limit). If you want or need two women, fine, but with all the women and beauties in the world, why do they have to be related ?