Who played Natalie doppalganger in Star Wars Phantom Menace?

There is no character named "Natalie Doppalganger" in Star Wars: The Phantom Menace. It's likely you are thinking of Natalie Portman, who played Padmé Amidala.

There is no "doppleganger" character in the movie, though Padmé does have several handmaidens who resemble her, and she uses them as disguises.