To be honest I'm not sure what I should be asking for then. To make myself clear - what I wanted to get was to have 2 'visually' full frames side by side. I tried changing the DAR setting from default to "Use 16:9 for both (not recommended)" but I didn't see any difference so not really sure what it does.
Now I also have just tested modifying sar in the __ENCODE_3D.cmd by:
1) removing sar completely --> this didn't do any change at all (Good question is
WHY?)
2) changing the value to --sar 1:1 --> this finally DID make the output video display 2 full frames side by side in their original ratio
Can you also please explain what the DAR setting (Settings -> Full SBS/T&B aspect ratio) does as it doesn't seem to do any change to me.
The reason why I am asking for keeping original aspect ratio of each frame is to be able to immediately see that the movie is full-SBS. Then I can watch it as 2D -- by zooming to the left frame, or 3D - in which case I would change the aspect ratio of it to 16:9 on the player to make it visually half-SBS.