There are times when a poster wants to update a thread but can't since he have already posted. The post may be valuable to the continuance of the thread. Also, if he just uses the "Edit" button. It is futile since people can't see a thread buried deep.
What I'm suggesting is, double post should be allowed but with a lag time. For instance, a person can't double post if he posted in the same day but if he posted the next day, next week or month. It should be allowed.
What do you think? I hope I presented myself clear