I'm guessing this only happens to replies to your own postings, right? When someone clicks "Reply to all" they send two messages: 1 directly to you and 1 to the mailing list which the list then also sends to you. You can't prevent this - it is entirely in the control of the person replying to you.
>When I get postings from some members I sometimes get two copies of the same message, I had this right from I first joined the group
