What does it mean if your hamster sometimes has 2 red eyes or 2 black eyes?

it probably has an abcess in its eye, and you should go to the vet ASAP. the least that could happen is the eye could be taken out. if you don't want to do that to your hamster, or put him through any pain, and you don't take him to the vets, then it is a criminal offence to keep him the way he is. he could be in a lot of pain already and can probably not see through that eye any more, so when you take him to the vet, you will be relieving him of the pain. this will n ot effect him, with only one eye, as hamsters have very poor vision as it is.