Seeing PPC tracking codes in Bing Organic SERP

[frith26]

When I search in Bing for a keyword that I am bidding on on both Yahoo and Google, the organic URL contains the tracking string from the PPC ad

How is Bing doing this?
What are the implications for this? I am assuming duplicate content will be an issue here!
What is the best way to fix it?

[bhartzer]

This happens all the time. Most likely someone has made a link to the URL that includes the tracking code, and the search engine spider has crawled the URL.

If you run PPC ads and include tracking parameters, people will click on the links (which they're supposed to do). They will end up bookmarking the URL and sometimes they actually will make a link using that URL.