How to use 'number_of_vms' option in service dialog


I am trying to use ‘number_of_vms’ option in the service dialog for creating multiple VMs but i am getting the below error after the 1st VM successfully gets provisioned.

VM Provision Error: Step [CheckProvisioned] Status [Error Creating VM] Message [Error: VM Clone Failed: The name ‘testvm’ already exists.]

looks like the second request is trying to create the VM with the same name as the first, is there a way to force the systems to use incremental names using service dialog? like testvm001, testvm002?