Perhaps the "How To Steal A Million" film tracks? I could be mis-remembering, though. Just a guess.
And weren't there a few of the "100 Rifles" tracks that had been damaged (or perhaps missing) in stereo, so were on that CD in mono only? Again, may be my fading memory....
Man, this is tougher than I thought.
A little off-the-topic: I assume if John Williams's "Dracula" is ever expanded to include the film tracks, it will fit into this category and they will be in mono because of damaged stereo tapes. Not that I wouldn't still get it --- any chance to have that complete score on CD is better than none.