Although they haven’t realised the news to the public domain just yet, as of mid-November adCenter will de-dupe ads by display url. Currently two sponsored adverts with the same display urls (example.com & example.com) can both be shown at the same time in one SERP. This move to allow only one display url per advert in a search results page will be in-line with what Google already have in place.
This may have a significant impact on advertisers and affiliates alike running ads using the same display url. In the similar way Google decides what advert to show, the advert with the highest click through rate (CTR)/bid will be served regardless of which ad is associated with the real trademark owner.
Of course if you have a registered trademark, aCenter can restrict other advertisers bidding on your terms.