According to Andrew Sandoval's book, The Monkees: The Day-by-Day Story of the '60s TV Pop Sensation, studio engineer Pete Abbott assembled a stereo master for The Monkees' fifth album, The Birds, The Bees & The Monkees, on March 19, 1968 that included the following songs:
Through the Looking Glass
We Were Made For Each Other
I'll Be Back Up On My Feet
Long Title: Do I Have To Do This All Over Again
P.O. Box 9847
Zor and Zam
Sandoval noted that "Today's master also features 'I'll Be Back Up On My Feet' and 'Valleri' in some form of quasi-medley probably achieved through editing. They will be completely separated and resequenced on the final release. Likewise 'The Poster' and 'Alvin' are edited together in Abbott's compilation to form a medley."
The week after this line-up was created, the album was recompiled in a different sequence, dropping "Through the Looking Glass," "Long Title: Do I Have To Do This All Over Again," and "Alvin," while adding Michael Nesmith's "Auntie's Municipal Court" and "Magnolia Simms," along with "Zor and Zam."
"Through the Looking Glass" would later be remixed for inclusion on 1969's Instant Replay, and "Long Title" would appear on the soundtrack of The Monkees' feature film, Head.
For what it's worth, when I'm listening to the Birds album, it's going to be the mono mix that gets the nod!