In lieu of fixing T372034, it seems that not only is Punjabi (Gurmukhi) appearing twice in the Universal Language Selector, but there are also around 30 other languages with redirects appearing twice as well. 14 of these languages are also included in @Amire80's list above.

1. адыгабзэ (ady-cyrl/ady)
2. تونسي / Tûnsî (aeb/aeb-arab)
3. azərbaycanca (az/az-latn)
4. تۆرکجه (azb/az-arab)
5. Batak Toba (bbc/bbc-latn)
6. भोजपुरी (bh/bho)
7. Chavacano de Zamboanga (cbk-zam/cbk)
8. qırımtatarca (Latin) (crh-latn/crh)
9. गोंयची कोंकणी / Gõychi Konknni (gom/gom-deva)
10. Fiji Hindi (hif-latn/hif)
11. ᐃᓄᒃᑎᑐᑦ / inuktitut (iu/ike-cans)
12. адыгэбзэ (kbd-cyrl/kbd)
13. қазақша (kk/kk-cyrl)
14. قازاقشا (جۇنگو) (kk-cn/kk-arab)
15. қазақша (Қазақстан) (kk-kz/kk-cyrl)
16. qazaqşa (Türkïya) (kk-tr/kk-latn)
17. कॉशुर / کٲشُر (ks/ks-arab)
18. kurdî (ku/ku-latn)
19. Ladino (lad/lad-latn)
20. ਪੰਜਾਬੀ (pa/pa-guru)
21. Влахесте (ruq-cyrl/ruq)
22. Taclḥit (shi/shi-latn)
23. tacawit (shy/shy-latn)
24. سرائیکی (skr/skr-arab)
25. српски / srpski (sr/sr-cyrl)
26. српски (ћирилица) (sr-ec/sr-cyrl)
27. srpski (latinica) (sr-el/sr-latn)
28. тоҷикӣ (tg/tg-cyrl)
29. татарча (tt-cyrl/tt)
30. ئۇيغۇرچە / Uyghurche (ug/ug-arab)

Link to the pull request: https://github.com/wikimedia/jquery.uls/pull/490

@abi_ @santhosh Could we get one of you to help review the patch (linked in a comment above)?

Following what we did for Punjabi to redirect pa-guru to pa here T372034, here is a first patch for this task which addresses an issue with data formatting for Tunisian Arabic:
https://github.com/wikimedia/language-data/pull/403.

If this patch is okay, we can repeat the same for languages listed in T195342#10123652.

@Amire80 Patch for you review for Tajik language data: https://github.com/wikimedia/language-data/pull/411

@Amire80 Patch for your review for Tajik updates: https://github.com/wikimedia/jquery.uls/pull/499

Change #1121436 had a related patch set uploaded (by Srishakatux; author: Srishakatux):

[mediawiki/extensions/UniversalLanguageSelector@master] Update `jquery.uls` from upstream

https://gerrit.wikimedia.org/r/1121436

Change #1121436 merged by jenkins-bot:

[mediawiki/extensions/UniversalLanguageSelector@master] Update `jquery.uls` from upstream

https://gerrit.wikimedia.org/r/1121436

Thank you for tagging this task with good first task for Wikimedia newcomers!

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A good first task is a self-contained, non-controversial task with a clear approach. It should be well-described with pointers to help a completely new contributor, for example it should clearly pointed to the codebase URL and provide clear steps to help a contributor get setup for success. We've included some guidelines at https://phabricator.wikimedia.org/tag/good_first_task/ !

Thank you for helping us drive new contributions to our projects <3

Thanks for claiming this task, @Nemoralis!

I also wanted to remind everyone that, since this task involves making changes for 30+ languages, multiple people can work on it together :) I see that @sathvik9105 and @Adityakumar0545 have expressed interest as well.

Opened draft PR: https://github.com/wikimedia/language-data/pull/431

Just like with az and azb T394873, it appears that aeb T396082 may also have another issue causing the language to still appear twice in ULS. Previously, it was observed that redirects can sometimes cause duplicates in the Suggested Languages list in ULS, as was the case with az. For aeb, it could be something else, for example, a redirect added in Names.php in MediaWiki core. Although T396082 is being closed for now, as the redirect has been fixed in the language data repository, something broader might still be causing the duplicate display. Currently, aeb only appears when you search using Tunisian arabic rather than the language code aeb itself.