Definitely, 'dn' and 'distinguishedName' are different things. The

Definitely, 'dn' and 'distinguishedName' are different things.  The
former is a pseudo attribute type used internally by slapd to represent
the distinguished name of an entry and its existance should not be
visible.  The latter is an "abstract" attribute type that is not meant
to exist in practice except as supertype of other dn-valued types.
So, the definition of attribute type 2.5.4.49 has been changed to be
just distinguishedName.  Work on the OPENLDAP_DEVEL_SCHEMA branch will
treat pseudo attributes especially and will not be visible to the
clients.