Oh, I know this one. Geonames imported coordinates that omit seconds, from US Board on Geographic Names publications; Ceb & SV wikis created articles based on Geonames coords; these got imported into WD.
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In the UK case (& presume same deal for other countries), we tracked down GeoNames' source to a US Board on Geographic Names publication, in which coords are given in degrees and minutes, omitting seconds.
So iirc that's about up to 2km out for UK / NZ.