https://bugzilla.redhat.com/show_bug.cgi?id=977063
--- Comment #2 from Pete Travis me@petetravis.com --- Hi Stephen, another quick observation for you.
There's a note reading: "At the time of writing, NetworkManager does not detect IP aliases in ifcfg files. For example, if ifcfg-eth0 and ifcfg-eth0:1 files are present, NetworkManager creates two connections, which will cause confusion. "
I'm reasonably confident that NetworkManager now obeys address directives in /etc/sysconfig/network-scripts/ifcfg-devname. I *think* that .../ifcfg-devname:0 style aliases are not supported, but successfully ignored.