This still happens with the redesigned CXStats page.

It is not obvious to me why there should only be one. There are two separate Wikipedias. Can you explain?

There are two separate Wikipedias.

The two locales are "nb" and "nn". The "nb" wiki is still at "no" subdomain, technically one translates to nb.

So we could remove one from the language selector, but we also would need to manually update the database for existing entries – or do it on the fly, but that is a bit icky.

'no' and 'nn' are separate Wikipedias.

'nb' and 'no' refer to the same language in the Wikimedia world (ideally, 'no' should be a macro code that refers to 'nb' and 'nn', according to ISO).

The way MediaWiki works now, it doesn't make much sense that both 'nb' and 'no' will appear in the same screen, be it a selector, a statistics table, etc.

In T95292#1399122, @Nikerabbit wrote:

So we could remove one from the language selector, but we also would need to manually update the database for existing entries – or do it on the fly, but that is a bit icky.

Updating the database would be nice, and getting new entries created under just one correct code would be nice as well.

No new entries using code no should appear after T132217: Machine translation in Content translation from nowiki to nnwiki broken. That should be confirmed by inspect the database after some time.

I can confirm the above.

mysql:research@analytics-store.eqiad.wmnet [wikishared]> select substr(translation_start_timestamp,1,6) as ts, count(*) from cx_translations where translation_source_language = 'no' or translation_target_language = 'no' group by ts;
+--------+----------+

+--------+----------+

+--------+----------+

Last one is from 2016-06-03