Duplicated Virtual Machines Have Same IP Address (View topic) • virtualbox.org

"Ok, that Ubuntu issue is a known problem. It saves the assignment of MAC ethX using an udev rule. Have a look at /etc/udev/rules.d and you will find a file 70-persistent-net.rules there. You can savely remove this file. This file is auto-generated by /lib/udev/rules.d/75-persistent-net-generator.rules. You can remove that file as well. From now on, the guest will no longer store the assignment between the MAC and ethX interface."