Actually, the evidence for Multiple personality syndrome is finicky and not definite. Psychologist disagree on the extent or even the realness of it, saying that it can't be possible to house multiple personalities inside a single mind. Its commonly used as an excuse to negative actions, so the legitimacy of it all is hard to find. That person with the 9 personalities, is probably horribly confused, or suffering from some other mental disorder, perhaps schtizophrenia.