I don't understand what the problem is of "reply all".
I got your email twice, that's the problem.
You can do something about it yourself.
I don't understand. How could I prevent you to send me a private email?
Read this again:
To prevent duplication you either send to the list from the same
e-mail address as that is subscribed to the list, or you specify a
reply-to address that is the same as the address that is subscribed to
the list.
I'm convinced that when the mailing list daemon sees that your address
is CC'ed to an e-mail, it will not send you a duplicate. However, this
doesn't work if you are cc'ed by an address that is not subscribed to
the list.
Jurgen had the same problem after the last mailing list disaster and it
seems he fixed it in this way.
Vincent