Hmm.  I do find irregularity when I try to combine a morph from the lower face with one from the upper face to create a simple test screening morph.  The motion differs in the two morphs.  It looks the same, but if you mix parts of different morphs or dial the morphs up to 10, the difference shows.  So that first idea might work, but only with more difficulty than I had hoped.

A quicker way might be to write a script which trims out all deltas which are smaller than a given threshold value.  Presumably the intentional deltas in the morphs are more pronounced than the background noise.

I'll tinker with the two ideas.

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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.