If there is one, I'd be interested to know what approach it uses.  There's been discussion of one, on and off, but I don't know that one exists.  The trouble with any Python script to switch UV maps in Poser would be that it would actually have to switch geometry, in one way or another, and each approach for geometry switching in Poser offers its own complications and limitations.  It could be done, but I doubt the result would be as easy to use, fast, or flexible as it would be in any software where a single geometry can be held in memory with multiple UV maps for that geometry.  :unsure:

In particular, the fact that Poser UV-switching would require actual geometry switching (until and unless some update gives us new options) creates difficulties for animation.  If the point is to animate two UV maps blending while a geometry morphs, complicated tricks would be needed to accomplish this.  The geometry switch would be on or off for all available options, with no gray area to allow any kind of built-in blending effect.  Overall, I think it would be simpler to just swap figures.  :sad:

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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.