The best way I found is to export the appliance, unfortunately. Unless you only want to make copies in which case cloning would be the best solution.
I use an external drive to store all my Virtual Images on so I don’t actually “export” them I just set up the appliance with the current files at my other locations. This allows me to have the same image and upload to the different servers (I chose stand alone servers instead of Nodes… not really sure why, I was just new at setting FOG up and I never re did the set up I know it’s going to change when I upgrade to 0.33 version but for now I just have multiple servers.)
I am partial to the snapshots feature. That and I use fairly antiquated technology, the ones that are on the phase out, for my imaging so I never had a GOOD server to build ESXi on, so the bad taste left in my mouth may be my own fault, but I never had good luck with VMWare.