Well, this is insanity making on several of the groups I read regularly.  It happens with far more than a single user and, in fact, the first topic I made reference to in my initial query is now 4 separate threads.  There is no logical reason for this, as it should be simple to use subject/title and time frame of posts in some coherent way to prevent this.  This isn't rocket science, and anything with the same subject/title in an e-mail message posted within, say, 24 hours of the last thing posted with exactly that same subject/title is virtually certain to be a part of an ongoing topic.