Why VirtualBox assigns the same IP address to two instance of VMs? Both use Host-only networking

Why VirtualBox assigns the same IP address to two instance of VMs? Both
use Host-only networking

VB version: 4.2.16
Guest OS version: ubuntu 12.4 LTS
Host OS version: OSX 10.8.4
I have created two VMs which use host-only network adaptors. These are the
screenshots from two instance of VirtualBox.


It seems like both machines got an IP of 192.168.122.1 for interface virbr0.
First of all I would expect both to be different. I also expect the IP to
fall in the range of 192.168.56.0/24 because it is specified so in the
preference:

So, why VB assign same IP twice to both boxes?