[Razor]

Good lord! Don't even think about it! Hamsters are solitary animals, and to try to pair them, especially after even the smallest period of seperation is asking for trouble, no trouble is an understatement. Bloodshed is the right word. It's unnatural even in the wild for them to live together. And like Souffle said, you'd be putting both your hamsters under immense stress by trying to make them companions.
The only way dwarves can remain in pairs is if they've been together since a very young age, never been seperated even for the shortest duration of time (It just takes the snap of a finger for a hamster to get extremely territorial). And even then, most hamster pairs don't work out.