<< I'm curious about why MoI export to OBJ (and perhaps other formats, I haven't checked) includes duplicate vertices. I was reading another thread here about Octane having problems rendering MoI output and the subject came up about duplicate vertices.>>

I don't think that the duplicate vertices in that case were due to a seam from MoI (since the duplicates are all over the place and not just on a seam). It was just due to a very sloppy mesh. That is why I doubted that the mesh came from MoI, since I have never seen MoI create random duplicate vertices all around the mesh. If you want to take a look at that mesh yourself, you can find it here: http://refractivesoftware.com/forum/download/file.php?id=10501

<< The question then becomes "why isnt Octane or Blender reading the true vertex normals from the obj file and screwing up the shading??

This question is for Blender or Octane though, not MoI.>>

Octane doesn't have a problem reading in normals from MoI.

Blender ignores normal information and calculates its own (which ends up messing up renders from MoI).