I tried to find an answer to this a few years ago, but it seemed it wasn't possible then (I suspect it isn't now either! - but what the hell!)
I have a three monitor system, that I mostly use for remote desktop. However occasionally it would be useful to have remote desktop on two monitors and use the other monitor for the local machine.
I know it is possible to have a single monitor full screen, or to stretch an RDP session across monitors, but this loses things like snapping etc.
P.S. this is a duplicate of this thread, but that was a couple of years ago, I'm hoping things have changed.