Trouble adding two normal maps to an object I'm having trouble adding two normal maps to a leather seat. I'm using the principled shader and each normal map has it's own uv map. When I add the second normal map it adds unwanted distortion.
This may not answer your question and I cant even explain what is going on but maybe this can help you. 

Since I cant explain this answer I will take it down if I get yelled at or downvoted. lol 

This is for using 2 normal maps (or more):





I have never plugged a normal map directly into displacement socket. I don't know if that is causing the problem or not.

I attached the .blend file so you can just append the node tree if you want.