Wikidata Property for an Identifier that Generally Has Just One Value, but Rarely Can Have Two or More Values for the Same Entity

Wikidata Property for an Identifier that Generally Has One Value, but Rarely Can Have Two or More Values for the Same Entity

The scheme of this identifier has generally a 1-1 relation to Wikidata, but occasionally assigns several identifiers for what Wikidata considers the same concept, e.g. concept "A" has identifiers "zza" and "zzb" at the same time.