One of my clients has english language websites targeted for USA and UK audience with some content variations but60%-70% of the content on site remains the same. The site is hosted in USA. One is hosted on brandname.co.uk and one is on brandname.com. The precuations that we have already taken to save it from being marked duplicates are: 1. used rel=alternate element for all product detail pages 2. currency in both the sites are different that is GBP and USD 3. have tried to differenttate the product by using different product specific terms like Publishing Year: vis a vis published in: Author Vis a vis Written by Format vis a vis binding type Add to cart vis a vis add to basket and so on What reamins the same: 1. Title structure 2. Description 3. Product Name 4. About the product text
You should consider changing the description (maybe translate it into the language desired), product name (if possible, if it is a branded product than leave it as it is, or ad something like Product Brand for Country), and "about the product text again translated, or if possible included in the description.