We've all heard about those poor psychiatric ward patients who claim and are convinced that they are some famous historical or religious figure. We treat this as a mental illness, but in the framework of idealism, do you think it is possible that these people simply start to REMEMBER?
At one point Bernardo wrote about the fact that we have no idea where memory is stored, and there are clues indicating that not in the brain (e.g. animals who can regrow their destroyed brain, yet will once again remember Pavlovian reflexes thereafter). Many traditional religions speak about that "memory comes from the Self" (i.e. the universal Self), and for you Steinerians there's the "Akasha Chronicles".
So is it possible that what happens to these people is that somehow, the mental framework that should keep their dissociation intact and letting only those memories through that the given alter had accumulated fails, and their identity gets confused / merged with an older alter?
If so, than other than a theoretical point, this would also have huge consequences concerning how to treat such people. It's one thing to be treated and written off as insane and locked away from society, being pushed by the outside world to think you are crazy, and another to have peeks into the beyond, which would not necessarily need to be cured, but simply understood and reconciled.