Love the two-fers, still love finding them in the record bins.
The Arlington Public Library, back in the days when you could still check out vinyl, had two of those two-fers I remember fondly:
1) Charles Mingus REINCARNATION OF A LOVEBIRD, which I didn't realize until recently that was a session from the early 70's. I've not seen it since, but I also found out it is available on CD, so there you go!
2) The Trane two-fer that paired TRANEING IN and SOULTRANE. This two-fer was pretty much my introduction to Trane, Prestige, and so much more in jazz. Talk about a starting point! I'd just started getting to jazz via my dad's Blakey records, so I was checking out as many jazz LPs that the library would allow. This was the one that got me hooked eternally into jazz. And so many good memories attached to this set.