I was right -- "Mirror" and "Name" do both have relatively short scores, shorter than I expected. Although its score did include a couple of never-before-heard library cues by Courage, which I assume will be on disc 5.
None of the original recordings here have been released before as far as I know, but new performances of cues from "Mirror, Mirror" and "By Any Other Name" were on Varese Sarabande's Star Trek Volume Two
, conducted by Steiner. Cues from those episodes that have not previously had a version released are:
Blackship in Space/Blackship Underscore
Evil Kirk/Evil Kirk
(Assuming the two "Blackship Theme" cues are basically the same)
"By Any Other Name":
Kelinda’s Question/Rojan Roars/Kelinda’s Kiss
There's a cue on the VS album called "Rojan's Victory," which I would speculate might be an alternate name for "Rojan Roars," but I can't be sure.
I'm curious about Discs 4 & 5. The Music of Star Trek
's scoring schedule list gives no information about "Patterns of Force," which featured a new motif for the Nazis and which credited George Duning as the episode's composer. I wonder, will that motif turn out to be a hitherto-uncredited piece of library music?