difference between two registry locations for HKLM\SOFTWARE\Microsoft\Windows\ and HKLM\SOFTWARE\Microsoft\Windows NT\

What is the difference between the two registry locations

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon:LegalNoticeText
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System:LegalNoticeText

While my question is asking about the LegalNoticeText i am more interested in the difference between the HKLM\SOFTWARE\Microsoft\Windows NT\ and HKLM\SOFTWARE\Microsoft\Windows\. I have searched online and can't find any solid information to explain why I have duplicate keys in two places and why CIS benchmarks suggest only the HKLM\SOFTWARE\Microsoft\Windows\ over the other one.

I don't have hard evidence or sources for this, but just my personal experience.

These are not duplicate keys. Yes, they exists in two places, but have different purposes and are both valid and one shouldn't be preferred over the over.

From my experience the Windows NT key was more used in the old days when the OS was actually called Windows NT, so 1993 to 1999, most core OS settings from the time can be found there and never changed after the renaming to Windows 2000. But newer settings were mostly added under the Windows Key, but if a sub-key already existed under Windows NT new values where added here too.

Just think of it as a historical fact, there are two locations for Windows OS settings.

In you specific case I think the LegalNoticeText under Windows NT is the system default, the one under Policies is used for Group Policies to overwrite that default.