One might think so, but in practice, my dock seems to not care which of my three players is inserted at any given time. Mostly I guess it's just training the ethernet plug to lie in the correct orientation. A hair either way might cause trouble.

HOWEVER, this is pure speculation from me, not something I have ever seen in practice on any dock I've shipped!

The ethernet trouble seen once by one user could easily just be the usual flakiness that I see all of the time (docked as well as not docked) -- DHCP just seems flakey at times. Mine now all use static IP, and work 100% reliably with that. DHCP works for them on my friend's network, just not reliably on my own. Dunno why, everything else on that same network/switch uses DHCP with nary a glitch.

Cheers