I guess that they don't see the R6 as having enough resolution, when you project 2 images to the 36x24 sensor. I didn't bother to check the image circle, but I would ass-u-me that it's a full circle for each "eye" so that would bring us down to - at the most - two 18mm circular images. If it's two perfect 18mm diameter circles, you'd use 58.9% of the image sensor so 26.5Mpixels in total or 13.25Mpixels/image path for the 45Mpixel R5.