i assume those two guys were the ones she made into her original "pets" (the zombies that follow her everywhere) from when she was introduced in season 3. I know that michonne had previous relationships with both the guys that became her first pair of pets, so i guess when she got these new ones she had flashbacks to those original guys in her dream. started off like it was before the outbreak, then gradually they change to their final mutilated states and she wakes up.
but that leads me to one other thing. i know the pet zombies can't attack michonne without arms and their lower jaws, but why dont they ever try? we know that zombies will try to attack people, no matter what condition theyre in, such as the decapitated zombie heads that desperately bite at people. but the magical combo of no arms & no jaw, and they instantly become totally docile, as do the nearby zombies. its a cool concept but never really made sense to me.
also, michonne taking out that mini horde was pretty badass, but she also seems to have lost her new pets already. oh well