Aidan,
 
    Duplicate postings from ARPA lists are quite common.  It is due to
a problem  with some  (actually, many) SMTP  mailers, when  sending to
distribution lists.  LISTSERV attempts to  clean up each piece of mail
that it sends, so you don't see all of the Received: lines, that would
indicate where the problem really  lies.  Specifically, the problem is
that the  sending SMTP  process iterates over  the list  of recipients
(from the  distribution list), dutifully  send copies of  the posting.
At some  point, it fails  to make a  connection to the  receiving SMTP
process (the  host is down,  or the gateway  to the host's  network is
down, etc.) The sending SMTP then requeues the posting for delivery at
a  later time.   If  you are  earlier  on the  list  that the  problem
address, you'll  get a copy the  first time, and then  again when it's
resent.  If  you are later that  the problem, you'll get  a copy after
the problem address has be passed.  Many SMTP systems will try to send
mail repeatedly for  up to three days before aborting  entirely, so if
you're an early address, you may see *many* copies.
 
    A good SMTP would only resend  to problem addresses, and skip over
them during  the first pass.  But  then, we all know  bad programmers,
right?
 
Ross Patterson
Rutgers University
Center for Computer and Information Systems
ATT et al  : (201) 932-3435
BITNET     : A024012@RUTVM1
ARPANet    : A024012%RUTVM1.BITNET@WISCVM
Snail Mail : PO Box 879, Piscataway, NJ 08855-0879