I was prevented from doing an advance online check-in with Emirates (while overseas) because - I was told later - my son and I have the same (first/last) name and their system couldn't handle it. Subsequently, the flight was overbooked and we got bumped (which would have been avoided had I been able to use their online advance check-in).
I still can't get my head around how their online check-in system was setup where this could happen.
updated for clarity