better dual lobe and roughness specularity in general

In these days I'm getting input from who I consider two great photorealism masters at the daz forum, namely "j cade" and "Siciliano1969". So from more tests I got that the dual lobe layer two, that's the upper one, does not take into account the surface roughness. That makes sense since the upper layer is more a smooth "top coat". So we have to remove the normals from the dual lobe second layer to fix this as shown below. Test scene included.

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Then this is the comparison with iray that now matches fine. First the iray layers one and two, then cycles. We can see in the second layer there’s no surface roughness.

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Also the iray default bump distance that I got by empiric method, seems to better match with 0.2 mm rather than 0.5 mm. A least this avoids ugly bumps in closeup renderings and also matches better with the dual lobe specularity so I guess it's generally better. Below a comparison with the default 0.5 mm while the images above are with the fixed 0.2 mm that matches better with iray.

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As a side note the iray top coat takes into account the surface roughness so we're fine and don't have to fix anything. Apart the cycles top coat being a simplified version I mean. Below the iray top coat.

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