That way we both get more traffic and make more money.
Since our partner areas on oursite are 87% similar, i am greatly concerned that we might get flanked for duplicate content even though the links are based at our URL.
On the other hand, i have been playing with the idea of setting a cookie from the url refereer field to allow links from our partners to go straight to our main url but to still allow them the branding their require around our content.
I don't think you need to worry about dupicate content penalties unless you actually have 100% duplicate pages.
Much content on the net is duplicate, and there are no problems seen.
Just remember it is very easy to create a checksum to check for duplicate pages, but much trickier to actually implement a reasonable duplicate content filter. Problem is many pages on some sites are very similar, although it's the nav and such that is duplicate, instead of the content.