LOL @ simon.
C'mon, QCA, if you're gonna dig up dirt on the Bible, there's much better stuff than this. I can't believe that the author couldn't get an answer from Bible scholars. Anyone who's even read a book about the history of the bible knows that many of the books are redactions and compilations of separate writings.
Most scholars believe that Isaiah was written by at least two people, probably more. Even if one accepts the idea that the all the prophetic portions were written by one person, however, there would be nothing to prevent him--or more likely, the compiler of his writings--from including a historical narrative from another source in which he figured prominently.