OS: Windows 11 2H22621.126522.
Issue: Even though Windows Explorer Option is set to: Open folder in the same window, each double click opens a new explorer window.
I have tried a few remedies including looking for this Registry entries from this prior post for a different version of Windows.
What you see is the designed behavior.
Windows Explorer now has a tabbed interface,and clicking a new instance of Windows Explorer opens a new Window (even though the Option says Same Window.
I checked this on 3 Windows 11 Pro V22H2 machines and that is how it works.
This keeps tabs in one Window separate from tabs in another window.
So this is the correct behavior as designed at this point.
Follow up:
In V22H2, Window Instances do not combine, and tabs cannot be removed from a Window.
This may change but that is the situation now.