If you accidentally assign a duplicate address to a VM, follow these steps to re-populate ARP cache with the correct information:
1. Change an incorrect IP address on a VM to what it should be, or shutdown the VM.
2. Log in to your server via DRAC.
3. Ping your default gateway from the server, this will update the router's ARP cache with the correct MAC address.
4. Now you can connect to your server as usual.
5. Disconnect a VM from virtual network.
6. Boot the VM and assign a valid IP address.
7. Re-connect VM to the network.
You may need to execute step 1 from server's console VIA DRAC. (there is a CLI interface available for the above steps - refer to VMWare manuals for details).