Multiple Personality Disorder (MPD) Dissociative Identity Disorder (DID) Multiple Personality Disorder (MPD), which is now called Dissociative Identity Disorder (DID), is a Dissociative Disorder. This disorder is when a person has two or more distinct personalities that often control the person’s behavior. This disorder has many controversies because of the fact that it is not scientifically proven. One personality is usually restrained and rather dull while another one maybe very outgoing and obnoxious. A person can have many personalities; there is no set number. Each personality acts different and the original p