How to preserve material names when copy/paste object from another Blender session ?

Hullo. I have 2 Blender sessions open, one has render scene and one session has object(s) what I want to use for modeling and testing materials. After I copy/paste object to render scene but material names changes, Gold becomes Gold.001 and so on.
My purpose is that materials are shared in both sessions because I use material library.
I have tried linked system and append but the result is same, if I change one material color which is not linked, linked objects materials do not change.

How do you handle materials when you dont do modeling in main project scene ?