The only reason I believe that those posts were not written by the same person are the dates - the time between Satoshi's post and Peter Todd's post. It's one day apart. If it was a continuation of Satoshi's thoughts posted mistakenly using another account, then it would have been mere minutes apart, no?
todd isnt satoshi nor is he carrying on with his own conversation.. but.. it was 1hour 27 minutes apart, not one day
11:59pm 1:28am
i read it as he was answering satoshi.. of course