Almost all the content on my sites, articles, and hubs get copies somewhere or the other. I myself have tried threatening to file a DMCA notice but honestly, it doesn't work!
You can either go ahead and actually file a DMCA notice, which will cost you money, or you have the option of just letting it go. It is after all the Internet; everything has duplicates online.
I personally have chose the latter. Since my content came first anyway I don't notice any fall in SERPs. In fact, sites with duplicate content are the one penalized by search engines; that's punishment enough. Unless of course you know you way around programming.
Most websites have backward security protocols. You could always *cough*produce the desired results*cough* with some programming knowledge.