DID voices -
Auditory memorys, trigger related take care of the trigger and the memorys stop replaying.
Sometimes more than one memory gets triggered by the same or different trigger into replaying which gives the perception of Alters having a conversation, take care of the triggers and the memorys stop replaying.
Medication does not stop the replaying of thse memorys.

I don't know much about Schizophrenai but what a friend goes through and this past month of research so I may be wrong here but here goes -

Schizophrenic voices
Chemical imballace, with the right medication and dosage the voices go away
voice content cannot be traced to a rerunning of memorys.
Voices are percieved as being outside the body coming from people places and things around the person.

(so far I have not found a professional that says the voices of schizophrenia is inside the the head. Course I have only just begun researching this)