[Mailman-Users] suppress duplicate when posting addressed to list and its alias name

[Sahil Tandon]

Many of our lists have full addresses in the form of 'foo-bar at baz.org',
with corresponding alias names 'bar at baz.org'.

When someone sends a message To:foo-bar at baz.org and also Cc:bar at baz.org,
his or her MUA sends two separate messages to the list which transmits
these duplicates to list members.  However, only one copy makes it to
the pipermail HTML archives.

Is there a Mailman way to activate, in the context of delivery, the same
duplicate suppression that occurs when archiving?  If not, I will have
to do this based on Message-IDs on input at the MTA, but I would prefer
to do it via the mailing list manager if this is already possible.

Thanks,
-- 
Sahil Tandon