Sorry, didn't mean to over-simplify. I believe they are two unique individuals who happen to share some common areas. Like two roommates in a shared apartment. Even though they share a unique connection and are physically linked the article states the twins have distinct personalities and their own voices and thoughts. That seems like two different people to me. DID is not the same, I've had the pleasure of working with a few as a psych nurse. This is one person, who takes on different personalities as a result of stress or trauma. Technically, in theory, one of the twins could later develop DID and she could have multiple personalities - but she and those identities would still would be separate from her sister.