Hi. Welcome to HC! Dwarf hams are very sweet and a lot of fun! Without pictures I couldn't say what you have but if they're from a chain pet store then they are unlikely to be Campbells and are most likely a "Russian" hybrid (which means that the two different species of Campbells and Winter Whites have been bred together). There are some health problems that this cross breeding can cause such as being more prone to diabetes so I think it's quite important to be fairly strict about diet - a lot of shop bought treats are far too sugary. There are some good threads on diet in the feeding boards that will help.
Also with pairs it's important to watch their behaviours as they can sometimes fight and if it gets bad they can draw blood so if they start squabbling then you may need to seperate them but again there are plenty of good threads on here for that as well as advice on how to make a suitable environment to minimise the fallouts.
Looking forward to learning more about them!
