I'm going to guess that most banjo music, at least in a style like bluegrass, is not going to be able to be uploaded here due to copyright reasons. I had a look on WorldCat for the piece you mentioned, Dueling Banjos
, and found that it doesn't appear to have been published at all earlier than the 1970s, and mainly in modern-style compilations of traditional (and possibly some newly written) works for the instrument. The reason I added "in a style like bluegrass" is that I'm assuming that for the majority of its history, it was not notated, so any actual editions of one of these works will be edited transcriptions of what is seen as a 'standard' version of it, quite possibly (almost certainly in student-oriented editions) with fingerings, suggested alternative figurations or passages, etc. What I'm saying is basically that probably almost any modernized edition of this music is going to be heavily edited, falling afoul of what is known as the 'threshold of originality
', and therefore cannot be uploaded here.
If there are exceptions, of course, anyone is welcome to upload them