Currently the only categories that tangentially allow for double posting are the RPGs section and the Literature section. This is because the nature of these boards sometimes necessitates posting new content to continue the story or game. Of course, these are still considered on a case by case basis when they're brought to our attention.
The entire point behind not allowing double posting is to let dead conversations and topics die. Maximus' suggestion is actually a brilliant workaround and I suggest doing that in the future.
Unlike a lot of other boards, the TTVBoard does not have an "age limit" on topics, so to speak. Because of this, we have to be fairly strict about double posting, as we don't close out entire topics if they're posted in after a few weeks or months, but we also don't want people keeping a topic alive solely by themselves.