Multiple vqfx boxes running on KVM have the same serial number

Hi Juniper gurus!

I'm running 2x2 leaf-spine topology with vqfx images on KVM. At some point some RPC calls started to take way too much time and fail with timeouts, so I decided to reboot the VMs using virsh:

me@kvm-server $ for vm in $(virsh list | grep -P 'junos-mcae.*(spine|leaf)' | awk '{print $2;}'); do virsh reset $vm; done

The problem with RPC calls timeouts has gone, but new problem appeared: all the boxes now would have the same serial number:

from jnpr.junos import Device
user = "user"
password = "password"

devices = [{
        "hostname": "<ip>.{}".format(ip),
        "username": user,
        "password": password,
    } for ip in xrange(9, 14 + 1)]

for device in devices:
    dev = Device(host=device['hostname'],
                 user=device['username'],
                 passwd=device['password'])
    try:
        dev.open()
        print("%s facts: %s" % (device['hostname'], dev.facts['serialnumber']))
    finally:
        dev.close()

prints following:

<ip>.9 facts: 130178177892<ip>.10 facts: 130178177892<ip>.11 facts: 130178177892<ip>.12 facts: 130178177892<ip>.13 facts: 130178177892<ip>.14 facts: 130178177892

Any suggestions on what I might be doing wrong? How is it possible to have serial numbers to be identical?