>My questions:
>Since <user@bitnode> and <[log in to unmask]> are now equivalent (am I
>right?):
> - Do I get e-mail from that list at all?
> - If so, at which address?
 
Yes, exactly as before the tag became known.
 
> - Does LISTSERV (or some other facility) go crazy figuring out whether
>   I want mail (setting for domain address) or not (8@8 address)?
 
Nope, it doesn't worry about it.
 
> - Do I need to do something, and if so, what?
 
You may indeed want to "clean up the mess" but that is not absolutely
necessary.
 
> - Will LISTSERV inform me of any now redundant stuff?
 
No, it's happy with the current (working) situation the list is in.
 
>My own  tentative answer is  to kill the <user@bitnode>  subscription at
>that point in time.
 
Well LISTSERV  has no  means to  decide which of  the 2  subscriptions is
"better" than the other one. You might have had the exact opposite setup,
anyway it's basically your business  and your decision not LISTSERV's. If
you send a  SIGNOFF command, it should remove the  address from which you
sent the SIGNOFF, and only that address. If you send a second SIGNOFF, it
will remove the second address.
 
  Eric