Duplicating / cloning volumes

Hi! Does anyone knows a way to duplicate volumes?
On each stack we are creating two volumes with rancher-nfs driver and external false. (check here)

We usually need to duplicate stacks to make tests or for training purpose, so we need to duplicate volumes also. I can solve stack duplication from ui, api or just creating a new stack, but I haven’t found a way tu duplicate volumes.

I’ve seen this volumes api documentation but I wasn’t able to achieve it.