I am not sure if people are aware of this, but I just did a small test and it works...
You can even use one decal (UV set) to layer color maps with transparency over each other.
Not sure if it helps a lot (maybe with 3d painting it could be nice for instance to animate wounds or skin changes or something like that?) but it was an interesting thing for me...
Best regards
*Fuchur*
video_stacking_color_maps_on_each_other.mp4
decal_texture_layering.zip