if you are using dual monitors and you would like to set up dual wallpapers on both the monitors. Then it’s not directly possible. I know that there is something called NView from NVIDIA. But i didn’t liked it too much. It’s my personal view.
After googling a bit i found nice tool called “wallmaster” which is free and source is also available at codeplex :
http://wallmaster.codeplex.com/Release/ProjectReleases.aspx?ReleaseId=23483
WallMaster 0.1.3 Download