Here's a tip for copying ESXi VMs.  Before making a copy, log in to the source VM and execute the following command:


# esxcfg-advcfg -s 1 /Net/FollowHardwareMac


With this setting, the management interface MAC address will update whenever the VM's MAC address changes.  Without this setting, you may end up with multiple VMs sharing the same management interface MAC address.