This one does exactly what i want: https://github.com/baldingwizard/Blender-Addons/wiki/Vertex-Color-Blend
Unfortunately its only for 2.79 and didnt work in 2.8+
This one does exactly what i want: https://github.com/baldingwizard/Blender-Addons/wiki/Vertex-Color-Blend
Unfortunately its only for 2.79 and didnt work in 2.8+