https://bugs.openldap.org/show_bug.cgi?id=9286
--- Comment #2 from corey@kaylors.net --- Maybe the published docs aren't reflective of the docs you're referencing, but the docs here http://www.lmdb.tech/doc/group__mdb.html#ga1206b2af8b95e7f6b0ef6b28708c9127 state
MDB_GET_MULTIPLE Return key and up to a page of duplicate data items from current cursor position. Move cursor to prepare for MDB_NEXT_MULTIPLE. Only for MDB_DUPFIXED
Clearly the desired behavior though, sorry for raising an issue.