Thanks for the feedback.
The Pro built-in OBJ-Exporter does have an advantage in that it automatically corrects 'skewed' textures by making unique-materials from them - unfortunately this 'method' is not directly available in the current API. However, the disadvantage of the the Pro built-in OBJ-Exporter is that it isn't accessible within the API [unlike the Collada-Exporter] so you can't automatically force it to take the defaults needed for Octane - and of course it's not not available to 'Free' users at all.
As a result it was decided to make a customized Octane OBJ-Exporter that would be usable by Pro and
Free users. So you [currently] have to manually select any faces with 'skewed' textures and use the context-menu to 'make-unique-texture' before running the Octane OBJ-Exporter tool.
The Octane OBJ-Exporter uses code very
similar to 'su2objmtl' so I can't see where its output should vary at all from that - but both
of their outputs will vary from the built-in Pro OBJ-Exporter IF there are 'skewed' textures.
If you edit the .OBJ files made by 'su2objmtl' and the Octane OBJ-Exporter you will see that the contents are effectively the same code for v/vn/vt/f etc.
Can you explain where you see the differences ?
However, before that please try the beta.d version that is now available...