[Mailman-Users] Turn off receipt of duplicate emails

[Elvis Fernandes]

Hello,

Does the mailman administrator have a command to turn off duplicate emails
to a user?

I have a mail list (a.list) that includes a couple of sub list's (b.list,
c.list).
Some users are members of both these sub lists.

Currently, if I send out an email to a.list, then users who are common
members of b.list and c.list will receive the same email two times.
Right? I want to avoid that.

Is there an option in mailman (for either the sysadmin or the user).

The user level subsciption option "*Avoid duplicate copies of messages?"
does not do this task. *

Best,
Elvis Fernandes