diberry - 5:08 am on Oct 14, 2012 (gmt 0)
Are you asking whether the search engine can tell the difference? If so, Google has stated they can't always tell which is the original source. But assuming your page has already been indexed, it shouldn't be beyond the bot to notice that the two pages are identical other than the unlinked link, and since the unlinked link refers to your page, yours has to be the original.
On a related side note, it's been noted around here that Bing is slower to index pages, but better at just never indexing scrapers, compared to Google. It's also been suggested that Google lets in scrapers on purpose because most of them run Adsense, but another possibility is that Google is prioritizing fast indexing and that doesn't leave time to do the checks Bing is doing. Whatever the case, it's always a 50/50 chance whether or not Google will detect scraped content.
I would definitely issue a DCMA, though. When I've done that, I've *never* had Google fail to determine that mine was the original content. And after doing that, I don't often see another scraped version of that particular page make it into Google - at least not in the top 10 pages or however many I search. I do believe this method helps.