libvirt users - Nov 2018 - Getting two different guest in the same network

Dear list,

Being a libvirt noob, I have some trouble understanding.
It is about getting two different guest in the same network.

***********

I've defined a network with libvirt. This is the source xml:

<network>
   <name>private2</name>
   <uuid>9684f2c6-6fd0-491b-9cb5-80ee268b01ce</uuid>
   <bridge name='br2' stp='on' delay='0'/>
   <mac address='52:54:00:b0:0a:c5'/>
   <ip address='10.0.0.1' netmask='255.255.255.0'>
     <dhcp>
       <range start='10.0.0.20' end='10.0.0.254'/>
     </dhcp>
   </ip>
   <ip family='ipv6' address='2001:db8:ca2:3::1'
prefix='64'>
   </ip>
</network>

There is no 'forward' identifier so this should define an isolated
network.

br2 Was not pre-defined, it appeard after defining this network with 
libvirt.


***********

ps aux shows:
/usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/private2.conf


***********

ip a shows:

11: br2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state 
UP group default qlen 1000
     link/ether 52:54:00:b0:0a:c5 brd ff:ff:ff:ff:ff:ff
     inet 10.0.0.1/24 brd 10.0.0.255 scope global br2
        valid_lft forever preferred_lft forever
     inet6 2001:db8:ca2:3::1/64 scope global
        valid_lft forever preferred_lft forever
     inet6 fe80::5054:ff:feb0:ac5/64 scope link
        valid_lft forever preferred_lft forever
12: br2-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel master br2 
state DOWN group default qlen 1000
     link/ether 52:54:00:b0:0a:c5 brd ff:ff:ff:ff:ff:ff

***********

virsh net-list --all shows:

  Name                 State      Autostart     Persistent
----------------------------------------------------------
  private2             active     yes           yes

***********

Then I start two guests with different MAC-addresses and differt UUID's 
Both guests are set on DHCP. They share the same network config:

  <interface type='network'>
       <mac address='52:54:00:xx:xx:xx'/>
       <source network='private2'/>
       <model type='virtio'/>
       <address type='pci' domain='0x0000' bus='0x00'
slot='0x03'
function='0x0'/>
     </interface>

Both guests take a lot of time to boot, waiting for network configuration.
Then they end up having the same IP address, not able to communicate 
with each other.

What am I missing?

Your advise is much appreciated.