Are you aware of any false positives of LISTSERV standard duplicate checking?

From: "L-Soft list server at LISTS.PSU.EDU (1.8d)"
               <[log in to unmask]>
Subject:      Rejected posting to [log in to unmask]
To: <[log in to unmask]>

Your message  is being returned to  you unprocessed because it  appears
to have already  been  distributed to  the  psulist  list.  That  is,
a  message  with identical text  (but possibly with different  mail
headers) has been  posted to the list recently, either by you or
by  someone else. If you have a good reason to resend this message to the
list (for instance because you have been notified of a hardware failure
with loss of  data), please alter the text of the message in some way
and  resend it to the list. Note that  altering the "Subject:" line or
adding blank  lines at the top  or bottom of the message  is not
sufficient; you should  instead add a  sentence or  two at the  top
explaining why  you are resending the  message, so that the  other
subscribers understand why  they are getting two copies of the same message.