Two of these overdubbed tracks have subsequently been released. The altered 1962 outtake of "Mixed Up Confusion" that appeared on the Japanese anthology Masterpieces (1978) and the original edition of Biograph (1985) almost certainly came from this source, as did the overdubbed 'electric' version of "House Of The Rising Sun" from Dylan's first album that was included on the 1995 CD-ROM Highway 61 Interactive. The other two overdubbed songs were "Rocks And Gravel" and "Corrina Corrina", both from the Freewhelin' sessions. Presumably, as with "Mixed Up Confusion", the original backing tracks were completely stripped off before the new instrumental tracks were dubbed on.
Wilson later went on to repeat the experiment with Simon & Garfunkel's "The Sound of Silence", without their knowledge; that one, of course, did get released and became a No.1 hit single.