Database error (Meta, no ontology)

From Mazeworld

A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was:

(SQL query hidden)

from within function "SqlBagOStuff::set". Database returned error "1062: Duplicate entry 'mzw-kumi_:pcache:idhash:1578-0!1!0!!en!2!edit=0!printable=1' for key 'PRIMARY' (localhost)".