Wikipedia dates shown twice + not following same style

In info cards from Wikipedia, the dates are shown twice: (YYYY-MM-DD)DD MON YYYY or DD MON YYYY(YYYY-MM-DD).

Follow the same style/format for all dates, remove duplication.

yeri How does Wikipedia show these dates?

In wikipedia the (YYYY-MM-DD) part is not there.

azdanov I am pretty sure we got this from wikipedia so it is there somewhere will have a look.

Is this maybe data provided by WikiData?