Jeanus - 2017-02-06

Hi,
I use Webmin 1.831 and the module webmin dhcp server : ISC DHCPd version 4.2.2
I have an dhcp server on a debian server version 8.

It works good but i can't configure a device on 2 differents networks. I have the error message : "You have not permission to create hosts with duplicate hardware address."
I need to configure it on two differents vlan.
Do you know the solution please?
Thanks you very much.
Bests regards
JD