I'm sorry but in all my years of rodent breeding and prepping for vet school I was always informed of the species that cannot breed, such as mice and hamsters, there hasn't been a single documented occurence, as a long tailed hamster does look mouse like, but isn't actually a mouse considering different gestation periods aswell the scenrio is highly unlikely.
Ah that explains it, most pet stores just say stuff for you to buy it, it's where the term "panda" and "black bear" hamster came from, I assure you then your ham has no trace of mouse, a lot of pet stores are either uneducated or just make things up for a sale.
and she's half long tailed
but they could be wrong, I don't know...