FBX export, extra textures get added.

I use blender 2.78c.

And i have weird problems when i export FBX with materials embedded.
I just got problem in the software, so i checked the FBX and it did add extra texture in the material slot.
I now have 2 roughness maps , one selected and one is just added without any assignment.

I know that blender export is going coo coo if a texture is not inside the same directory as blend file. It start to copy in the case i did have the normal map that where a second texture to the albedo texture. Only because the albedo texture where in different directory !

You see this problem when you export the FBX with embed textures and then import that FBX.
Just tried it by removing the wrong textures and it did came back after export.

I do not see how this can happen,and harder problem. how to fix it !
And i need to use FBX. It feels like a bug.