Baffling network

[compdoc]

If you were to look at the file:   /etc/udev/rules.d/70-persistent-net.rules
you might find that the list of adaptors in the file is messed up. It's a
problem I've seen several times when I add or remove adaptors a few times. 

All you need to do is delete the list of nics from this file and reboot, and
Ubuntu will recreate the list. Of course, afterwards, you should have eth0
and eth1 back, so you might need to tweak your network settings in
/etc/network/interfaces     if you use static settings.