The virt-clone tool does not know how to modify the internals of a disk image when cloning.
When using virt-clone, various state from the previous guest would remain in the new guest. In particular, udev rules referring to the old network would remain, causing a brand new interface to be brought up on the new guest (with a new name, eg eth1).
We have provided two new tools: virt-sysprep can "cleanse" old state from guests, and virt-sparsify which can make guest images sparse.
Users should use virt-sysprep and virt-sparsify either as a replacement for, or in conjunction with, virt-clone. See the man page of virt-sysprep for full instructions: