It's deja-vu all over again...as the famous quip goes...and it surely is an amazing phenomenon to experience because it is one of those things that you cannot express to someone who has not themselves experienced deja vu. I really doubt there is anyone who has not at sometime or other said to themselves 'well I'm sure I said and did this very thing I'm doing now...before this!' How can one explain it?
Personally I'm sure it is a supernatural event.
In other words, when we pop ahead or behind in the space-time continuum, deja vu occurs. We are creatures of more than just blood and bones and synapses, I believe, and deja vu is just one of those excellent examples to assure us of such a fact. There is more in heaven and hell than is dreamt of in your philosophy Horatio...to quote Shakespeare, and truly who could ever deny that supernatural events, like experiencing an event for the second time, just as it occurred the first time, is not evidence of our mysterious world and our remarkable human lives.
Of great interest to me, and related to this topic, is the one we saw illustrated in the movie Ground Hog Day, where Bill Murray was trapped in a deja vu experience, but one which he was aware of as it was happening, which added an extra layer of deja vu on top of the existing layer! Now that is a mind-bender!
I suggest one watch this movie backwards, in reverse, and see what happens. I am dizzy right now just thinking of it.