I don't think it matters as long as they are 2 males or 2 females. (I adopted 4 females from the local animal shelter and they made a mistake sexing them – they were 3 females and 1 male – so now I have 16). Learn how to sex them yourself or take them to a vet to make sure you have two of the same.
I have both males and females. My males fight each other more often and more viciously than my females do, but it seems that my males' cage is a bit cleaner than my females' cages.
I have both males and females. My males fight each other more often and more viciously than my females do, but it seems that my males' cage is a bit cleaner than my females' cages.