Resync LDAP master > backup

In the LDAP on our backup server, I found some residues of a user.
I found the user when browing the LDAP using Apache Directory Studio.
The user is not on the master server anymore.

Is it possible to force a sync between master and backup?

One possibility is to simply join the DC Backup again, e.g. by running the command univention-join. That’ll copy over the whole LDAP directory among other things and is non-destructive to other data stored on the server.