One of my co-workers has 2 dwarf hamsters. She now wants to adopt a third one. She keeps them in separate cages. She wants to handle the hamster so she hopes that it is still young or already comfortable with human touch.
Dwarf hamsters are very happy living together, it’s Syrian hamsters you have to separate. On the other hand, like a lot of animals, they don’t always accept intruders immediately. If they’re different sexes you’ll want to separate them.