Multiple Personalities: Do They Really Exist Multiple personalities- the existence of two or more distinct personalities or personality states within one person. In actuality, up to ten or even more personalities can coexist within one person, some documented cases have revealed over one hundred. But, the question remains, what exactly is the multiple personality disorder (MPD)? First I will look at what exactly the disorder is. It is, in simple terms, many complex personalities all inhabiting the same body. At any given time, one of ....