[exim] Catchall Mailbox (duplicating)

Hi there,

I've having an issue with exim4 which is duplicating emails sent to a
"catchall" mailbox, Basically any emails going to a specific domain land
up in this mailbox.
The only time I get a duplicate is if the email is sent to more than one
recipient in that domain, then depending on the amount of recipients it
duplicates into the box.

Is there anyway to tell exim only to deliver that message once into the
mailbox, instead of delivering into the mailbox for every recipient?

Router
# Routing method - catchalls
catchallmailbox:
        driver = accept
        condition = ${if eq{${lookup mysql {SELECT COUNT(*) FROM 
`courier`.`mailboxes` WHERE `user` = 'catchall@${quote_mysql:$domain}' 
LIMIT 1}}}{1}{yes}{no}}
        transport = catchallmailbox

Transport
  catchallmailbox:
        driver = appendfile
        directory = ${lookup mysql {SELECT `maildir` FROM 
`courier`.`mailboxes` WHERE `user` = 'catchall@${quote_mysql:$domain}' 
LIMIT 1}}
        maildir_format
        mode = 0777
        user = Debian-exim
        group = Debian-exim
        directory_mode = 0777

Kind Regards,
Michael da Silva Pereira