I got it working. I did the above then named it Dual Monitor Output and then click the gear and enable "use this for audio output" or something similar. To test open each individual Studio Display Speakers 1 and Studio Display Speakers 2 and test for each by selecting mute... Guess both mine are fed from Studio Display Speakers 2. Then go back to Dual Monitor Output and click Configure Speakers and they should be both on Front, left and right. Then go into Studio Display Speakers 2 and test for right and left, on mine this is the right display and left is left only on this panel and so is right. So in stereo mode, we will have double right and left I suppose. i.e. left panel has both right and left and right panel has both right and left.
I played with a few arrangements and it seems stereo makes most sense. I changed the left panel to front left and right as front center. Set the gain at 16.0; right monitor set left speaker as front center and right as front right.
Not sure how this will work with movies, but it's just my desktop audio and sounds good and full with just music.