I advise you to add real unique content and continue building backlinks.
Honestly in what degree duplicate descriptions are harmful for an affiliate site only Google can tell.
Watch the Matt Cutts video below...
If you want to stay on the safe side you can choose to...
- not display product descriptions
- rewrite product descriptions
Another more drastic way is to block your store from the search engines via your robots.txt file and drive traffic to your store via your content pages.
Instead of trying to rank your store pages you try to rank your content pages. More background info below...