Poser 2014

Hello. I have been studying this problem and I know about polys' self-shadowing and I switched my cameras all to spotlight. Still, I'm sad.

I m guessing the problem may be in my props. I imported clothes made in Marvelous Designers and then IMPORTED AGAIN WITH REVERSED POLYS to be able to see the backside of the garment. Then I export them together as one OBJ and import back, and use them. The rendered image is full of terrible dark spots.

Preview:

Rendered:

I removed textures and everything in Materials Room:

ticked @Remove backfacing polys@ in Render Settings, still the same.I imported a prop once, with no double inverted copy and here is the difference:

Preview

Rendered

I would appreciate any advice on what I can do here.