A doppelganger's tactical abilities are limited by their intelligence. So when fighting one someone will have to use skills that can be used more intelligently.
Everyone can have a doppelganger.
You don't become a doppelganger, doppelganger exists by God.
I saw my doppelganger across the street, and it was like looking into a mirror.
Doppelganger Inc. is no longer existing.
It's because your doppelganger can pretend to be you or she might be standing right behind you when that person saw your doppelganger.
I would consider the antagonist as the creature he is. Not who he is but what he is, a Doppelganger.
Doppelganger - 1997 is rated/received certificates of: UK:PG
The cast of Doppelganger - 1979 includes: Donna Loney
Doppelganger - 2009 II is rated/received certificates of: USA:PG
It means that the doppelganger is coming after you or it's trying to tell you something.
Doppelganger
You don't.