Policy to handle duplicate Wikidata items

[marfox]

Example

The MusicBrainz baseline matcher said: Q12622425 -> c6cee938-adea-44f5-ad87-f42630233f1d

but Q8966672 is the real one and already has the MusicBrainz ID above.

Possible actions

• if the external ID already exists on Wikidata, don't add it to the other item;
• keep track of the match & publish a log: this is a bot activity, see #91;
• add the match source item as a candidate for the Wikidata merge game.

[marfox]

The validator could check inconsistencies like QID 1 points to MusicBrainz artist X, but MusicBrainz artist X points to QID 2.