Unity high res mesh brighter than low res mesh despite using the same material

Question

I'm currently making an LOD system for terrain. I have a high-res mesh:

And a low-res mesh:

As you can see, the high-res mesh is significantly brighter than the low-res mesh. They are definitely using the same material. Is there a fix for this?

Edit: Fixed. This was caused by multiple instances of the mesh being on top of itself (which was further caused by the subdiv mesh lingering between runs)

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