Problem: Wikidata allows in various ways to add duplicate data: this makes the maintenance of the items more difficult and uselessly increases the size of Wikidata (which is bad for the SPARQL query service, storage space etc.).The cases I consider are: duplications between labels and aliases in the same language; duplications of date-statements (due to different encode of the same date); duplications of references (two exactly identical references, or the two references identical except for a different retrieval date)
Proposed solution: make it impossible on server-side to save exactly duplicate data; make it more difficult (e.g. show a message before saving the edit) to add nearly duplicate data (this regards the case of references identical except for a different retrieval date)
Who would benefit: Wikidata community (the maintenance of items becomes a slightly smaller task); SPARQL query service (the size of the items becomes slightly smaller)
Permanent duplicates are a slightly different problem, caused by the fact that an item cannot have two sitelinks for the same Wikimedia project; truly unpleasant, but I would leave it out from this task. Same sitelink in two items is relevant, I add it above! --Epìdosis 10:41, 9 February 2023 (UTC) P.S. I would, but it seems it's too late. Anyway, it is another sure case of possible data duplication. --Epìdosis10:44, 9 February 2023 (UTC)[reply]
Note: you can also very easily add a new Wikidata item via Wikishootme. It is a great tool, but when there are no geocoordinates in an already existing Wikidata item about the same subject, then you do not see it in Wikishootme. So you always have to check first before you use the Wikishootme tool for making a new Wikidata item; but who does that? So in that tool the automatic check should also be implemented. --JopkeB (talk) 12:36, 11 February 2023 (UTC)[reply]
Support --M2k~dewiki (talk) 18:45, 10 February 2023 (UTC)