I recently got a very cheap offer for 1,5 monitors (2 identical old 1280x1024 monitors and one incompatible stand) that I built together into dual monitor setup. Problem was that in order to fit stand's mounting screws, monitors had to be in portrait position, while one is rotated 180 degrees compared to other display (see fig. 2).
Windows 10 recognised both and I managed to set up two logical displays (fig. A). Sadly, most programs are not designed to run in portrait mode, especially video players and games. Solution seemed to be Intel HD Graphics Control Panel's Multiple displays->Collage option. It merged physical displays into one 2048x1280 logical display. Problem is, that one monitor shows image upside down, while other shows correctly (fig. B). I can't rotate one of displays, but I can rotate entire virtual display. My desired result is on figure C.
Clearing up for question: how to merge two displays to one logical, while one needs rotating by 180 degrees? (doesn't have to be Intel Collage solution)
System spec: Intel i5 6400 (Skylake, integrated HD 530 GPU), Windows 10 Pro, Gigabyte B150-M D3H motherboard, plenty of RAM and two HP 1740 monitors (using VGA and DVI-I)
Figures 1 and 2 show monitors placement and arrow shows upper side of monitor (where manufacturer planned it to be). Figures a-c show how OS treats displays, where arrows shows centre of logical display on monitors physical placement.