I also have them in D:\My Documents\Object Dock Library
You can just delete these folders the same as I have and you won't have any problems. One reason for NOT putting them in the "My Documents" folders is that the custom Plus/Minus images won't show up if they are in there and you will end up with the ugly default Plus/Minus images which don't match anything. The other reason is that there is no need for them.
They were put there so people could use the .dockzip extension for auto installing docks...but doing this like I said cancels out the custom Plus/Minus images.
Just put "all" your backgrounds...tabbed...non tabbed...side docks...and tiles in the Programs/Stardock/Objectdock/backgrounds folder and you'll be good to go.