I checked, and it doesn't leave it as a failed quest in the filtered Journal. Unfortunately, I did not check and see if it left it as failed in the unfiltered journal. But the last time I played it through and did it the way the posts say to: Fail one or the other... It did show one as failed. When I did it the way I said, "Following the Fat Lout dialogue a couple of times until Balin Attacks me" I received lots more XP, did not get a rep increase, and the quest was shown as completed...
Try it out and see what happens.
