CL 791 must exist in other editions, but I have not seen them. KZ-1 is a sampler album issued to get people to want more Kostelanetz albums. Many of these covers are great other than the Steinweiss ones, imho.
I have been introduced to lots of music by my collecting of Steinweiss and other covers. I never liked classical music composed before about 1960 until I listened to Steinweiss’ Paganini violin concerto played by Francescatti. I would never have imagined liking Mantovani until I listened to Steinweiss’ Mantovani Plays an Album of Your Favorite Tangos – which is now a favorite album of mine. This is of course the function of good packaging, to get people to want to experience what is inside the package. Kostelanetz remains the exception. I can’t imagine why he was so popular that they gave him his own sampler album. I can’t imagine ever listening to anything he recorded. And this from a person who likes schlock. It is remarkable how things that were once popular are now obscure, but it is equally remarkable that so much Kostelanetz is in print on CD. Everyone to their own tastes, I guess.