> The other person will get frustrated and disconnect and reconnect a few times, and finally give up and read a book...

That makes me really reconsider my past struggles with this form of Internet access.

Time to consider instead: walk through the plane, look angrily at the other passengers, one at a time, asking: "Do you use 192.168.x.y?". That can solve the problem

Or convince the flight attendants to including “MAC address spoofing” in the spiel about destroying or tampering with lavatory smoke detectors.

Presumably there is a way to find out which other wireless client is impersonating another in a confined environment like an airplane.

A multicast packet might vary based on physical distance to the imposter?