I first learned about Deja Vu from the movie The Matrix (the first movie or the good one). When Neo sees the cat twice just before Morpheus is caught.
I have experienced this my self quite a few times even though it was not as dramatic as the movie, its really a strange and wonderful feeling.
Kind of amazing that after all these scientific advancements we still can't explain this phenomenon.
Our brain is more complicated than anything out there in the real world. Its humbling even when we have advanced so much in our scientific knowledge.