Hmmm, you might be right, as the extension is changing material values on the gltf model itself, so if you have multiple instances of the same model, all of them will probably use the same material. Let me see if something can be done here.
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The new version was just released and it solves this problem!
Check out release notes!
Thanks! this actually helps alot, By the way can you make it so theres an action for changing color of a model but by its material slot? like in the MeshMaterial extension? I say this because i use that extension but it has the problem that you already fixed but also has the color by slot feature that this extension doesnt have yet, if this could be done it would be awesome but if you wont do it its alright, just a suggestion!