Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1194620
Description of problem:
I created an alias interface and define eth0 in identifier, Form was submitted without any validation error and UI accepted it.

Ideally UI should raise a validation error as you can't create two interfaces with same identifier

here is the snippet from provisioning template:

1. primary interface
   real=`ip -o link | grep 52:54:00:34:ac:fb | awk '{print $2;}' | sed s/://`

cat << EOF > /etc/sysconfig/network-scripts/ifcfg-$real
BOOTPROTO="dhcp"
DEVICE="$real"
HWADDR="52:54:00:34:ac:fb"
ONBOOT=yes
EOF

1. eth0 interface
   real=`ip -o link | grep 52:54:00:34:ac:fb | awk '{print $2;}' | sed s/:$//`
   real=`echo eth0 | sed s/eth0/$real/`

cat << EOF > /etc/sysconfig/network-scripts/ifcfg-$real
BOOTPROTO="none"
IPADDR="192.168.100.122"
NETMASK="255.255.255.248"
DEVICE="$real"
ONBOOT=yes
PEERDNS=no
PEERROUTES=no
EOF
---

Version-Release number of selected component (if applicable):
sat6.1 beta snap3
Satellite-6.1.0-RHEL-6-20150217.0

How reproducible:
always

Steps to Reproduce:
1. create a new host and add an interface with same identifier as of existing one
2.
3.

Actual results:
no validation error

Expected results:
validation error should be raised on form submation

Additional info: