btw - the LDAP scheme does not need any change for that.
in the example above the CN=team1@example.org,CN=alias,CN=mail,CN=zentyal,CN=Configuration,<baseDN of your server>
just needs a second entry in the attribute maildrop.
Then postfix will forward the mail to both (or more) addresses.
So I think this would just need some change in the webadmin UI...
Tried it using phpLDAPAdmin to change the attribute value...
regards
Lukas