USN rollbacks when im****ting VM DC's into isolated VM Lab

I've done this on physical machines a million times, with VMware GSX and 
copies of production virtual domain controllers on ****table hard drives,
and 
have NEVER had this problem, I had never even heard of a USN rollback
until 
I started cloning my prod VMDC's into my isolated lab ESX box.  The VM's 
that I put on ****table hard drives and brought into the physical machine
lab 
replicated with the root DC even thougth they had a higher number than the

root.  Why is this happening here, now?  Is it going to mean that for VM 
restoration of my forest I have to start with the newest VM by date and 
bring in only by gradually decreasing USN/HWMV #'s ?