I only say duplicates but I think this could be extended to several other flagging reasons. Since accepted answers/upvotes don't get reverted on questions I see people sometimes cut and paste the answer from a duplicate question without flagging as duplicate. In the end they can usually score a few upvotes and even an accepted answer.
Found this related question: Give an incentive for finding duplicate questions
Seems to have a lot of popularity but nothing ever happened
Jeff on Dupes
Those arguing for “remove reputation from dupes” have no idea of the Frankenstein monster you’d be creating.
That would be an awesome rep-denial tool for griefing others, first of all.
Second, it creates a MASSIVE disincentive to participation — even if you had no idea there were duplicates, you could be bushwhacked at any time even if you contributed a fantastic answer. Oops sorry dupe! Zero rep, buddy! Bzzzzt! Go away! Take your awesome answer elsewhere!
Incentives are fine, but penalties are an incredibly bad idea and would actively hurt users and the network.
I guess this answers my question, even if I disagree with jeff.