How to monetize websites with duplicate content?

I have few websites almost exclusively with duplicate content.

I realized that they started to receive nice traffic. Search engines mostly.

What are the best ways to monetize the traffic?

I don't want to risk my adsense account, although I would make a killing with it..

Anyone know if amazon or chikita is against duplicate content?

I really appreciate your input guys.

I use my adsense account with my sites which contains duplicate contents without any problem for a long time ago

depends on the content try clickbank its the best

Yeah i did the same with ad sense with no problems.