When playing most full screen games, the game ..for the lack of a better word, 'shoves' the desktop of my second monitor off the screen, away from the monitor which is running the game. Usually the margin that it creates is about an inch to an inch and a half wide, and in that space it shows the desktop background.. all the icons, windows, and the windows bar at the bottom of the screen are pushed over.
Is there any way to stop this?

Are your monitors different resolutions? I have this happen when the game's resolution isn't correctly set. For example if your main monitor is 1920x1080 and you are playing in 2560x1440 resolution, some games will shove over to the second monitor.

That's quite possible. I'll check later today when I'm actually at my desktop and can run a game. It'd be awesome if the fix was that easy