I see, maybe theymos need to fix this and not to allow double posting IMO to avoid same post lurking in some section if this incident occur again.
This doesn't happen often enough to justify making a change within the code, especially because the additional resources it would use to check whether someone has previously posted the same message would greatly outweigh the benefits of preventing users from posting duplicate content. Duplicate content is usually made on purpose where users look to spread their product or whatever to as many users of the forum as possible. Of course, as stated above the correct way of going about this is reporting the thread, and linking back to another thread of the duplicated content.
Sometimes this sort of duplicate content does go unnoticed, and it results in two different conversations at which the best thing to do would be to merge the threads together. However, I think that entirely depends on the quality of discussion. Usually what happens is either the most active thread is kept or the one that was posted first. However, sometimes a thread that has been posted after the oldest one has better quality discussion, and is more active therefore sometimes its more appropriate to remove the older thread in that case.
