I assume that when you refer to "associative personality disorder"
you actually mean dissociative identity disorder
Schizophrenia and dissociative identity disorder have similar symptoms and are sometimes hard to distinguish between. That being said, I haven't been able to find any cases where a patent has been diagnosed with both (It may be possible, I suggest further research.)
It is possible for a patient with dissociative identity disorder to be unaware of one or more of his/her alters. I have no idea about one alter killing another though.
When researching topics make sure to use scholarly articles. Either use - https://scholar.google.com.au/
or, if you are a university student, there should be a library of articles available to you online through your university.