same existing replies with a different style ( some only copy past )
The only one solution to this has a limit in replies in every thread to avoid same thought and limit on pages(15-20 pages I guess)
OP may lock the thread if they meet the limit on replies.
and while the merit system was created to solve that problem he kinda of failed because people still doing same posts for an obvious reason signature bounties
No, I think there is an improvement in the forum since the merit system was implemented by sir theymos, everyone was trying themselves to have a quality post and hoping that every post count they have they earn merit as well.
What do you mean by spam? if they have the same thought with the OP's post still it is counted. That does not matter how long or short that you have posted as long as relevant to the topic and sharing idea.