On February 19 1965, The Beatles were in the midst of recording the soundtrack for their upcoming second movie eventually entitled "Help!" at EMI Studios number two and created a rarity.
After three takes, "You're Going To Lose That Girl" (an original Lennon/McCartney tune written and sung mainly by John) was completed and a production acetate for the film was mixed in mono. This production version of the song is missing the piano and the overdubbed bongos (added the next month). There is also a completely different Harrison guitar solo in the middle of the song. Whether The Beatles intended to leave this song as it is for the moment or not is pure speculation. The released commercial version has the further overdubs as well as a new guitar solo. The song can be found on the vinyl bootleg "Not Guilty" as well as on the CD bootleg "Help! Sessions".
Here it is on youtube: