Say it with me: Doppelganger
Doppelganger (noun) - a ghostly double or counterpart of a living person.
Back in the mid-90s I worked at a little fast food chain called Burger King in Lincoln.
It was there that I met my doppelganger. I was 17 at the time, he must have been 27-30.
Ironically, his name was Chad too. My co-workers thought I had done 'something different' until they realized the other Chad wasn't me. It was uncanny. He didn't think so, but everyone else – including me, did.
I've always thought Natalie Portman and Keira Knightley look alike. In fact, Kiera doubled as the queen in Episode One.
IMDB says, "The similarity between Knightley and Natalie Portman meant that during the filming of Star Wars: Episode I - The Phantom Menace (1999), their own mothers could not tell them apart once in makeup." ~ http://www.imdb.com/name/nm0461136/bio