Mites can easily travel even across a room and they can live off the host for a somewhat long amount of time. You should have both hammies treated and clean everything, dump bedding and food and hope that you get rid of them. I had a lice issue recently but I also researched a bit on mites and they are apparently a pain to get rid of. I know this post is late but I thought I should warn you anyways.

How is Kenco now?