Delusional identity disorder, also known as “impostor syndrome”, is typically manifested by the patient’s conviction that a person (most often a close person) is actually another person, and that the real person has been replaced by another person, and that the patient most often believes that the two persons existed at the same time, and that they are accompanied by other symptoms, such as delusions of grandiosity, and that the person being replaced may also be the person’s own personal belongings, or even himself/herself. The person who has been replaced may also be the patient’s own personal belongings, or even himself or herself has been replaced, mostly seen in schizophrenia and organic mental disorders. Another kind of delusional identity disorder is typically manifested by the patient’s conviction that many people around him, (mostly unknown strangers) are in fact some kind of his (familiar) double. Various means of metamorphosis, cloning, etc. are used, mostly accompanied by delusions of relationship and victimization. The former is a delusional denial of real identity, the latter is a delusional affirmation of non-real identity.