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