OK Let's clarify something.
Multiple Personality Disorder (MPD now known as Dissociative Identity Dosirder - DID)is a medical diagnosis and requires a very particular set of conditions for it to exist. Most often it is the direct result of early childhood severe and most often repeated abuses.
The vast majority of people raised as JWs, or raised in any cult, do not fit into the criteria for MPD/DID.
However, what cult members do have is a cult personality and the real self. The real self can be expressed when outside the field of the cult world where they can let down their guard. The cult personality is triggered by anything that has to do with the cult. Even an innocent question about the cult is enough trigger the cult personality to take over.
At meetings or when with other cult members the true self is suppressed. The true self may or may not be aware of the changes in how they behave. Those who live the double life will find the stress of living this way more and more difficult as time goes on. Over time they will allow their true self more expression.
Being DFed and still going to meetings is an extremey stressful thing to do. Sitting in a room and being ignored by everyone - I did it for one meeting and that was enough for me. My heart goes out to those who sit through it to get reinstated.