You Don't Bring Me Flowers (Neil Diamond/Barbra Streisand) 

Neil Diamond originally wrote this song to be a brief theme for the opening of the TV show "All That Glitters," but when the show concept changed, the song didn't fit any more, so Diamond expanded it to be a full song. He released it in 1977, and Barbra Streisand covered it in 1978. Radio DJs at the time started mixing the two versions into a duet, and the two singers finally recorded it as a duet in 1978.
Other Neil Diamond songs I've recorded include:
"Play Me" ( • Play Me (Neil Diamond) )
"Be" ( • Be (Neil Diamond/Jonat... )
"Cracklin' Rosie" ( • Cracklin' Rosie (Neil ... )
"Love on the Rocks" ( • Love on the Rocks (Nei... )
"Hello Again" ( • Hello Again (Neil Diam... )
"I Am...I Said" ( • I am...I Said )
"Song Sung Blue" ( • Song Sung Blue )
Other Barbra Streisand song I've recorded include "Evergreen" ( • Evergreen ) and her version of "Chromolume #7/Putting It Together" from Sunday in the Park with George ( • Chromolume #7 / Puttin... .