What causes walls lighting to be different?

I've a scene with only 1 directional light, a few spot lights and reflection probs off of a demo scene.

I've duplicated a wall and it suddenly looks different, does this look familiar to anyone?

 

You need to bake lightmaps.

If you have TWO walls standing at exact same spot then they can appear overbrightened depending on your rendering pipeline (the effect should happen in Forward Internal Renderer). That would happen if the pipeline is using additive multiplass rendering.

 

In future post in the correct part of the Unity forum.