There are cases when spammer copy your website data on their site and you came across of them after 1 year or so till that time your damage has been done. This is 1 case, what to do when there are lots of cases you can find for your own content duplicate issue.
I just had a search on the google for one of my client content, and i found plenty of sites had copied his data totally with no curtesy or link back or something.
we have contacted some of them but nobody turned up, this is also not possible to get the content changed entirely on regular basis as it is not easy for 10000 page sites or so..
Unless some of the popular spiders don't rectify their algos to identify authoritative sites for specific content, you will see this problem.
You can get around it, but it will be very expensive (initially at least), as you need to ban the spider who doesn't bring you to the top results for original content. And get around the scrap bots of course either feed them with low value content or ban them.
Your content will still be distributed to spiders who do recognize you as the author.