I try to transfer the boss model into gmod。

I tried to save the shape files ,I want to adjust the muscles of the boss but the normal map does not match,Is the normal map itself just like this?
This is because the character mesh has two sets of UVs, one is for the diffuse and the other for the normal map. In game both are active at the same time.

You will have to pick one, either create a new normal map or a new diffuse that match the other texture.

Unless gmod supports having two different UVs active at the same time for the same mesh.