Let It Be / You Know My Name (Look Up The Number)

From Wikipedia:

The single used the same cover photographs as the Let It Be album, and was originally released on 6 March 1970, backed by “You Know My Name (Look Up the Number)“, with a production credit for George Martin. This version includes orchestration and backing vocals overdubbed on 4 January 1970, under the supervision of Martin and McCartney, with backing vocals that included the only known contribution by Linda McCartney to a Beatles song. It was during this same session that Harrison recorded the second overdubbed guitar solo. The intention at one point was to have the two overdub solos playing together. This idea was dropped for the final mix of the single, and only the 30 April solo was used, although the 4 January overdub can be heard faintly during the final verse. Martin mixed the orchestration very low in this version.

The single mix made its album debut on the Beatles’ 1967–1970 compilation album. Original pressings erroneously show the running time of 4:01 (from the Let It Be album), and not the single version’s running time of 3:52. This version was also included on 20 Greatest Hits, Past Masters Volume 2 and 1.