@Jeremy Cheng - The rule against duplicate threads is referring more to when a players posts the same thread more than once, either in the same forum or across multiple forums.
While it's good to check to see if there is already a thread active for the topic you wish to discuss or suggest, it is not a requirement. There are often multiple threads, by different authors, making the same or similar suggestions. They may have different views or perspectives on how to approach the ideas. As long as there isn't a designated sticky for that topic, or one player has not copied & pasted another player's thread, it's fine for more than one player to have a thread on the same subject.