I don't believe you need updatedn.
example :
syncrepl rid=51 provider=ldaps://ldap.example.com type=refreshOnly interval=00:00:01:00 retry=60,10,300,+ searchbase="dc=example,dc=com" filter="(objectClass=*)" scope=sub schemachecking=off bindmethod=simple binddn="cn=replicator,ou=Service,ou=Applications,dc=example,dc=com" credentials=example
syncrepl rid=123 provider=ldap://ldap.mydomain.com type=refreshOnly interval=00:00:01:00 searchbase="dc=mydomainr,dc=com" schemachecking=off updatedn="cn=Manager,dc=mydomain,dc=com" bindmethod=simple binddn="cn=Manager,dc=mydomain,dc=com" credentials=secret