Does it matter>? Most of Bachs works is similar in nature anyway, he uses the same formula to generate all his counterpoint most of which is robotic. His best work with any soul is Siciliana (although I doubt if he even wrote that). I can write in the style of Bach and I can tell you as a composer theres no inspiration or emotion required to write in that sort of style just a good motiff and then follow that to the end. Why do you think he was able to churn out so many composition? To compose a Nocturne in the style equivallent to that of Chopin, now that is emotionally taxing and very difficult even for a seasoned composer. His prelude and fugues are over rated but they make good sales for publishers.