The correct number is somewhere between a multiplier of 1 and 2 depending on the setup of the display. But 2x 4k screens is only 16 megapixels, and so it also depends on where the other 7 megapixels are.
I can't edit this comment after 5 days but anybody coming along and find this - the multiplier is very close to 1. Go up a bit and find the sibling comment with the four links. Very good explanation of the difference between the monocular binocular FoV is buried within.
The correct number is somewhere between a multiplier of 1 and 2 depending on the setup of the display. But 2x 4k screens is only 16 megapixels, and so it also depends on where the other 7 megapixels are.