Forget the creepy references to Xenu. I ran across an 818 page document created by a member of the Church of Scientology who claims to have worked with L. Ron Hubbard in the early days of the cult. I have excerpted what I consider to be the most hilarious ramblings I have run across in the document below the break. This makes the Xenu mythology seem small by comparison.
The original source can be found at http://freezoneearth.org/pub/Super%20Scio.pdf
One recent example was in 1963 when president Richard M. Nixon launched a nuclear war that destroyed the planet. As we all began dying in droves, the prison machinery was used to restore a copy of the Earth taken in 1957. We were all conditioned to go back to what we were doing in 1957 and life picks up with a second pass through 1957 to 1963. Of course they intervene slightly and Kennedy is elected by the barest margin. Since he begins introducing major changes and because everyone unconsciously expects something bad to happen in 1963 anyway, he is assassinated and things begin to settle back down to their normal course. Nixon even gets to be president later with less ill effects.
These "backup" copies of the earth appear to be taken every 5 years in February of the years ending in either a 2 or a 7 (i.e.. 1952, 1957, 1962, etc.).
When they restore and earlier version, they don't like to back up too far because they have the problem of the growing population (as more prisoners are added). Pushing earth time back too far gives them a host of newer prisoners who have no place to go. Small numbers can be handled by using animal bodies for a brief time, but large numbers require setting up "holding tanks" on yet another copy of the earth further sideways along the 4D axis. This gives us a bunch of weird "preternatural" earths that some people will have experienced just before birth (and right after the previous time they died in this lifetime).
As you can see, this makes a terrible jumble of one's history. Nobody in their right mind, catching a halfway glimpse of the truth, would believe it, because things are not in the simple logical order that you would expect. You wonder why his recollection of Christmas 1957 doesn't match the facts? Maybe he's recalling a different time that he lived through 1957. Does he remember a funny incident when there seemed to be old steam boilered fire engines on the streets of modern New York, well that's a much earlier pass through the 1950s and things were slightly different. We have been reliving the 20th century for quite a long time.
A person's actual experience might include quite a few reincarnations on earth. But he might have lived through the last one or two incarnations a large number of times and he might even have another incarnation "up in the future" that he's been through a couple times as well. And in between, there might be visits to heavens, hells, pre-birth worlds, and even a few stints where he was forced to work in the between lives administrative area to keep this whole complex show on the road. Now mix in tons of heavy conditioning to keep him confused as all hell, and you have a true picture of today's human being here on Earth.