Steps to reproduce:
- Open https://en.wikipedia.org/wiki/Special:Search
- Click on "Advanced". URL changes to https://en.wikipedia.org/w/index.php?title=Special:Search&search=&fulltext=Search&profile=advanced
- Click on "Search". URL changes to https://en.wikipedia.org/w/index.php?title=Special%3ASearch&profile=advanced&search=&fulltext=Search&ns0=1&profile=advanced
The URL contains now the parameter profile=advanced twice. This is redundant.