Do you know that System Center Virtual Machine Manager (VMM) lets you create an identical clone of a running VM?
Yes! you do not even have to shut down a VM . How cool is that!
1) While going through the cloning process wizard in VMM, choose to leave the NIC disconnected
If you do not leave the NIC connected, you will have duplicate IP addresses on the network, when the cloned VM boots up.
2) After the cloning process completes, remember to run sysprep.
Yes, there have been some reports that VMM runs sysprep when it creates a clone, but I have confirmed myself (using psgetsid utility) that the clone and the original have the same SID and have the same hostname. They are virtually identical. So, you MUST run sysprep.