How do you deal with Duplicate content across domains?

Just wondering how do you guys deal with the Duplicate content issue in terms of Google SEO across 2 domains havng exactly the same products but for different countries?

We operate 2 sites - One of which is aimed at worlwide customers (.com) and one is aimed for the local country, both on separate domains. After we started our new local country site, our SEO has been totally screwed up and not sure what should we do in terms of SEO to get it back on track.

You need to change the targeting in google analytics to worldwide for Site A and the local country for Site B.

Where possible, it's best to paraphrase content, even going as far as rewriting from scratch.