You can create a new container just rename your ZFS volume. I do this all the time to "clone" a LXC on ZFS. E.g. use disk 100 for disk 101:
Code:
zfs destroy rpool/proxmox/subvol-101-disk-1
zfs rename rpool/proxmox/subvol-100-disk-1 rpool/proxmox/subvol-101-disk-1
You can also clone to get a real CoW approach for Proxmox/LXC