Yep duplicate contest is an issue. The savvy datafeed affiliates go into the merchant feed with something like Excel and re-write the descriptions. I just blogged about how to do that recently here it is.
"Teli Adlam is the developer of the
WordPress Datafeed Import Script which is an Affiliate Datafeed to RSS Conversion program, so rest assured she knows her stuff when it comes to datafeeds. Teli is also one of our VERY knowledgeable 5 Star Affiliate Forum Moderators so I wanted to share a recent blog she wrote about making feeds unique.
The Affiliate Datafeed Unique Content Myth
"Using the same datafeed files as other affiliates doesn’t mean you can’t have a unique affiliate website, however; there are a couple ways. It does take a little more effort on your part (not much, about 30 extra minutes preparing the datafeed depending on size), but the results may be surprising."
INFO 4 Merchants - Discover how to make GOOD feeds & learn the problems most feeds have.
Brian Edwards » What The F*** Do I Want A Product Feed For?
"Historically product feeds are poorly formatted / infrequently updated / have incorrect information / have poor or no category structure. Wait - no that is actually still the case"