Ubuntu Stealing IP Addressses

I'm stumped on this one.

Ive created a basic Ubuntu KVM using 18.  DHCP, and hostname is kvm18.
I'll clone this antlet, change the network adapter (New MAC address) and change the
hostname to kvm20.

When I start the kvm20 antlet, it steals the ipaddress from the running kvm18 antlet.
If I shutdown and restart kvm18, it steals the ip address back.

I cannot figure out why this is happening.

Any hints?

Hi anaglyph:

Yes, that is the correct procedure (to change the MAC address) in XML.

After logging into the antlet, what MAC address do you see listed after running this command:

ip a