Thanks, everyone.  I may not have been clear about my problem.  I don't need to transfer UV sets between objects, I need to convert a texture graphic designed for one UV set so it can be used with the other UV set.  I need to move the pixels around on the texture map image (not a UV template, but an actual texture), so they fit into the new spots on the modified UVs, right.

Ten years ago I would have spent a month fighting with PoserPython and PIL and cursing a lot, to try to build such a thing.  My programming skills, like my google-fu and my general internet communication skills, are pretty rusty these days.  Dang.

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.