Hi HnH - the best advice is to get your hamsters from a breeder rather than a pet shop.
All petshop russian hamsters (not including roborovoskis here) are hybrids, ie a cross between the Campbells hamster and the Winter White. This cross breeding makes the hamsters prone to health problems but in particular diabetes, so you would need to be careful about the foods you feed and avoid sugary foods, including fruits etc.
If you can get your pair from a breeder with the National Hamster Council (NHC), then the hamsters will have a pedigree, will be much less likely to have health issues and you will also know their lineage, which I find interesting.
Buying from a breeder does not mean that you 'll pay any more than you would in a store but the advantages are huge.
Keeping a pair of hamsters together doesn't always work out but a more successful breed to keep together are the roborovskis. These are really cute fluffs and can't be cross bred. They can be more of a breed to watch, as they can be tricky to handle as they are very fast and they can jump! They are incredibly entertaining though. People have much more success, generally, keeping robos together as they are more sociable with their own breed.
I have a robo, two hybrids (not together as they are not from the same litter), a winter white and I'll be getting my second pure winter white next weekend. I love all of mine to bits, as everyone does and I would be hard pushed to choose one breed against another. I definitely avoid petstore hamsters now that I know much more.
There are lots of things to do when keeping pairs together, duplicate wheels, toys, water bottles etc, having a large cage without any levels, as that can cause territorial fights, lots of hidey holes, so they can have cover and houses that have more than one entrance/exit so that one is never trapped.
So lots to think about - whereabouts are you, as people might know of breeders close to you or you might be able to get along to one of the shows held by the
NHC.