Most likely a hetro beige. Do you know the color of the parents?
It doesn't matter if its hetro or homo beige unless you plan on breeding it.
First, they should be pedigreed to breed and to me this looks like they are from the same litter so I would not breed brother and sister. Definetely do research before you start thinking about breeding.
If the pet stores get them they have to come from somewre. Which means there is a breeder or one that ships in. Definetly don't breed those 2 chins. Siblings should never be bred.
If the belly is white, it is a standard. If the belly is is gray, it's an ebony