second mesh looks darker

first mesh with transparent textures is ok. Copy that to the other side, it looks darker as if both were added on top of each other. (same unchanged texture region)
This is in x-plane, any ideas?
Many thanks

If you mirror the mesh, it flips the normals as well (and it will look darker because Blender will not do double-sided drawing by default).

Use the flip normals operation to get the brightness back.

Thanks but I only did copy with shift-d.

There are two meshes one in front of the other in the same object. The front has textures with transparency.
Probably has to do with opengl draw but maybe there’s a switch in Blender for such? No blend did remove completely the transparent textures which is not what I need.

Tbh, I don’t understand what you mean, could you please upload some screenshots or a blend file?