In the class net.irisshaders.iris.compat.sodium.mixin.copyEntity.cull, it is exactly the same as Sodium's EntityRendererMixin class except that the Iris one uses Mojmap for mappings. This has been found in Iris 1.7.0.

If these exist for a good reason, why is that?

This was needed in the past; and may still be needed soon. so I kept it. If it's causing a problem, I can remove it.