How do you edit a face/hair?

[XunAmarox]

Well, I got this response on NifSkope forums:

 

Some years ago it was necessary to duplicate the mesh in UV MODE (in Blender) or generally (in 3DSmax) to get a double sided texturing.

This way you got such meshes with a lot of duplicates.

 

If they aren't removed completely (so you create non- manifold meshes while removing duplicates) you will also get such artifacts.

 

BTW: I think that older versions of NIFskope were more efficient to remove this "diamond effect" then the recent builds.