I think it would still work. I think you'll end up both getting all of the network packets, in which case the higher-level protocols will ignore the ones meant for the other device. TCP and UDP both have source ports as well as destination ports, but the source ports are usually picked arbitrarily, so the different devices will have connections on different ports and will discard any packets bound for ports they don't have open. And TCP also has sequence numbers (which should be chosen randomly), so even if you ended up on the same port for a TCP connection, your packets are very likely to have different enough seqnos that you ignore each other's packets.