The two folders are not the same.
Fonts Disabled
Fonts_Disabled
I think there are a variety of reasons for fonts to be moved to a 'disabled' folder.
Each folder may have been created by different software, either some app you installed that may have supplied additional fonts - or a result of using some font management utility. Different developers likely will have different opinions about how those folders are named - so two disabled folders, with different names.
Are the fonts in each folder different?