Hey guys for a long time I have been trying to figure out how to get separate wallpaper for each monitor and I finally found a pretty simple way to do it. I'm using Linux Mint 17.2 Cinnamon on my gaming pc. I followed this guide.
What I did was install Nitrogen form the software center. Then open nitrogen and under Full Screen I selected which screen I wanted the wallpaper on then hit Apply and then repeated that step for each monitor. Then like the guide stated I made a start up script that said nitrogen --restore. That was it now I have different wallpaper for each screen.