Displacement modifier "keep normals" option

In displacement options EEVEE is restricted to only using displacement modifier.

When you use the displacement modifier with material, that already has a normal map you end up with a surface with exaggerated doubled normal information.

Options to solve this would be:

1. To not use normal map - but in return you lose micro details if the displaced mesh doesn't have a high polycount.

2. Transfer normals from a non displaced copy of the mesh - but you will have a situation when your workflow stops being non-destructive, or slows down, cause data transfer is computationally heavy on high polycount.

Both choices are not perfect, so i would suggest an option for the displacement modifier to not alter normals. That way we keep benefit of raycast shadows on the geometry, and surface detailed by normal map without need for high poly count, and slow workarounds.