Dana,
I recall hearing that explanation a long time ago. It seems to violate some basic rules of cause and effect in time travel theory tho.
To have a future self come back and try to take over your former selves and fail wouldn't that knowledge of events motivate you to prevent the future self from becoming evil in the first place so the future evil self should not exist to come back and try to hijack your past lives?
It's all very confusing and probably time travel would be more complicated than we can imagine.
"The days have gone down in the West behind the hills into shadow...How did it come to this?"