Herbeck/von Herbeck
Hi, James,  Well, I think there are three separate questions:
 The two articles I merged were most definitely about the same person, unless 2 people with virtually the same name, the same nationality, working in the same field, shared exactly the same day of birth and exactly the same day of death.  Technically possible, but extraordinarily unlikely, I would suggest.  
  Now, there may indeed have been another Johann Herbeck who worked around that time, but I'm no expert and I've never heard of such person.
 As to why the Bruckner biographies have him as Herbeck and not von Herbeck, it's probably because he got his "von" only in 1874, three years before his death.  For the great bulk of his life, he was simply Herr Herbeck, so it's appropriate to refer to him that way in a biog of another person.  For an encyclopedia article, however, he gets his full final name.  

This is a very handy source for some further updates to the article.  Cheers.