It shows up as one device. The res you get depends on your source. You won’t get full res if your device only has an older HDMI or Display Link output. I’ve go

It shows up as one device. The res you get depends on your source. You won’t get full res if your device only has an older HDMI or Display Link output. I’ve got it set up for occasional PIP with a Bay Trail home server. That device has an HDMI out that does max 1920 x 1080 and won’t do the full width of 2560 x whatever.