Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site cbosgd.UUCP
Path: utzoo!linus!philabs!seismo!harpo!floyd!vax135!ariel!houti!hogpc!houxm!mhuxl!ulysses!cbosgd!mark
From: mark@cbosgd.UUCP
Newsgroups: net.news
Subject: Re: dup articles
Message-ID: <613@cbosgd.UUCP>
Date: Thu, 17-Nov-83 13:53:28 EST
Article-I.D.: cbosgd.613
Posted: Thu Nov 17 13:53:28 1983
Date-Received: Sat, 19-Nov-83 01:56:30 EST
References: <4112@amd70.UUCP>
Organization: AT&T Bell Laboratories, Columbus
Lines: 4

The from lines don't matter, it's the Message-ID that does.  You didn't
enclose subject, date-received, or newsgroup, but I expect the two
were over 2 weeks apart and so your system had forgotten about the first
one (in your history file) before the 2nd came in.