see resolution
From the Vcenter server right click the VM and select remove from inventory.
If the VM is required at a later date, browse from the Vcenter server to the data store where the VM is stored, then browse to the directory of the VM right click the xxx.VMX file and select add to inventory and the old VM will be see again by the Vcenter server.
Note before adding the old VM to the inventory it is probably best to have removed the restored VM from the inventory.
