When I build my initial xml file using the clone feature it uses the MAC address of the server I created the xml file on.
-snip-
<interfaces config:type="list">
<interface>
<bootproto>static</bootproto>
<device>eth-id-00:1c:23:cb:7e:aa</device>
<ipaddr>10.120.160.231</ipaddr>
<netmask>255.255.254.0</netmask>
<startmode>auto</startmode>
<usercontrol>no</usercontrol>
</interface>
</interfaces>
-snip-