Error while cloning LXC container

Hi, I try to clone an LXC container from Cloudmin. It detects correctly my 2 network interfaces and gives me the choice to manually provide the 2 new IP adresses, that I prefer to do instead of relying on automatic allocation. Next step fails with this error : "Creating clone of LXC system xxxx named yyyy .. .. failed : Only 1 IP address needs to be supplied, but $2 were provided"

And I'm stuck :( Any help please ? I'm happy to provide debug info as needed.

Virtualmin version: 
Webmin version: