query: SELECT ?item (COUNT(?collection) AS ?count) WHERE {
    ?item wdt:P6379  wd:Q3912134.
    ?item wdt:P6379 ?collection.
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE]". }
  }
  GROUP BY ?item HAVING ( ?count > 1 )
  ORDER BY DESC(?count)