Simlpygon is not processing the Anatas the same as a model with one armature, and its having trouble, and having to rename things, and its making extra objects
With this example, with one armature, the error did not happen
Quality of life features:
The Simplygon Unity plug-in is built with USD (Universal Scene Description) as intermediate file format and is dependent on the Unity USD package.
https://hackmd.io/_uploads/SJFWtKNjh.png
https://hackmd.io/_uploads/HkeNFFVo2.png