I actually submitted this as a bug a couple months ago - Jeremy at MasterpieceVR responded very quickly saying it was quite difficult to fix and that they would work on it. Thank you Jeremy for your response.
The Issue: MasterpieceVR exports duplicate faces when exporting geometry made with the Brush tool. This results in two models in the same position - one with outward facing normals and another with inward facing normals.
It seems like it would be a simple - remove overlapping faces or duplicate vertices, - but tools like vertex merge (Maya) weld both side together and it creates strange geometry.
I just wanted to flag it here, hoping other people might chime in if they have the same problem .
And even better, if anyone has any solutions for cleaning up brush geometry post obj/fbx export.