Just to close this subject, I finally figured out what was happening to cause duplicated posts of large messages.
I use a hacked up version of the Perl LWGate GCI to publish my list to a web page. One of these pages has a "Most Recent" listing of articles. I use rc.local.s20 to add messages to this mailbox and then run a script to delete the oldest message, keeping the count at 100. (you can see it at http://www.sportster.org/cgi-bin/lwgate.cgi/XL-LIST/archives%5Ccurrent/curr ent/subject/ if you are interested).
I have to create a copy of the message, since I actually deliver it to a mailbox. For some reason, on larger messages (>4.5KB), my script was retruning an error exitcode. Therefore, procmail though the message had not been delivered and there was then two copies of it which continued through the rest of the SmartList processing. I had to add and "i" to the recipe so that the exitcode was ignored.
-- Doug Mansfield