[libvirt] how to duplicate an vm?

I am trying to duplicate an existing vm. While the VM was down, I copied the image file, copied the xml file and manually fixed the xml file to have a different VM name, and point to the copy. The copy now works, but the original disappraeed from virt-manager. When I try to "restore" it I get: Error restoring domain '/var/lib/libvirt/images/fc11-copy.img': operation failed: image magic is incorrect What am I doing wrong/how should I replicate a VM? Thanks, Dan