The condition you are referring to is called Dissociative Identity Disorder (DID), formerly known as Multiple Personality Disorder. It is a complex psychological disorder characterized by the presence of two or more distinct personality states or identities within an individual. Each identity may have its own unique set of memories, behaviors, thoughts, and emotions.
In cases of DID, one of the personalities may have experienced traumatic events, such as abuse, while another identity may not have any awareness or recollection of these events. This dissociation of memories and experiences is a coping mechanism that the mind uses to deal with overwhelming or traumatic situations.
It's essential to note that DID is a rare and complex disorder, and individuals with DID often require specialized therapeutic support to understand, manage, and integrate their different identities into a cohesive sense of self. If you or someone you know is experiencing symptoms that suggest dissociative identity disorder, it's important to seek professional help from a qualified mental health professional.