Manuscript Becker III.8.51, owned by the Universitätsbibliothek Leipzig, contains four fugues for organ or keyboard, from Friedrich Wilhelm Marpurg. They were copied from an unknown source by one J.A. Dröbs (if I read the insciption correctly). This Dröbs was not a very reliable scribe, as there are several obvious mistakes in the manuscript that is additionally often very difficult to read. The scores of these four fugues contain here and there some gueswork of what was actually meant and probably deviate in certain spots from Marpurg's original. As long as I do not have another source for these fugues however, this is for now the best I can do.
The first is a fugue in B flat major. Though the manuscript notates the fugue on two staves and the inscription of the manuscript mentions "or keyboard" ("a. f. Clavier"), the music works best when played with the pedals. The score is therefore rendered with three staves. If someone wants a two staves score, just let ke know,
The recording was done with the Hauptwerk software and the sampleset, made by Sonus Paradisi, of the Janke organ in the Stadtkirche of Bückeburg (https://www.sonusparadisi.cz/en/organs/germany/buckeburg-janke-organ.html).
Score available here: http://partitura.org/index.php/friedrich-wilhelm-marpurg-fuga-in-b-dur