@michelleevanhorck Katherine was a doppleganger as well. Once she became a vampire though, she was no longer considered a doppleganger because her blood couldn't be used to break the curse.
@MsSocialbutterfly08 The music is all of the time doing that. lol. When Stefan and Elena are together at the lake house, the song playing in the background talks about how the relationship is failing but the people pretend everything is ok. The music of TVD is very telling.
@michelleevanhorck Katherine was a doppleganger as well. Once she became a vampire though, she was no longer considered a doppleganger because her blood couldn't be used to break the curse.