query: #title: Single value (other than warning)
  # Complex constraint from [[Property talk:P2758]]
  # this property generally contains a single value other than [[d:Q23817739|warning <small>(Q23817739)</small>]]
  SELECT ?item WHERE { ?item wdt:P2758 ?value . FILTER ( ?value != wd:Q23817739 ) } GROUP BY ?item HAVING (COUNT(?value) > 1)