Does auto instancing of static meshes work for all material instances of a material? or just each material instance individually?

Does auto instancing of static meshes work for all material instances of a material? or just each material instance individually?

For example if i have 2 material instances of the same material with a minor variable change like roughness parameter. Do those 2 material instance batch together or are they considered seperate?

Each separate material instance assigned to a drawn object incurs an additional draw call, even if there is only a minor change in variables.