What is the song playing in Code Geass Episode 14: Geass vs Geass
The song is Masquerade, which is Track 13 on the first OST according to the metadata on my iPhone/iPod.


  Masquerade
  Vocals: Hitomi
  Lyrics: Kuroishi Hitomi
  Composition: Kuroishi Hitomi


While I can't time the song perfectly to where I believe it starts in the episode, one point that makes me believe they are the same song is at 0:51 of the song which matches the song at 20:54 of the episode (in the link)