Recognizing Copied DVD's?

I recently bought a DVD from ebay (lock stock and 2 smoking barrels - directors cut), it’s got all it’s original packaging and is in great condition. The actual disc has a murky gold bottom, this is usually found on copied discs. It plays without error and looks like the original from the top side however. How can i check this is deffinately not just a good copy?

Software?

dvdinfopro will tell you all you need to know.