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Hi there, I am in a very similar situation with multiple manufacturers on my EComm site. You are absolutely correct in adding uniquely valuable content to the category pages. You can use the category pages to target key terms and engage users. Content on category pages is especially useful for targeting branded and long tailed key terms. In this case, the Canonical tags will not help you, because the duplicate content is not on pages within your domain. If you had the same product description on two products on your site, then the canonical tag would be appropriate. However, when you use that tag you are telling the engines that the authoritative page should be the page that ranks, which means there is a chance the other pages won't rank. If you use the "no follow" tag, your pages will not be crawled by bots, which means you have 0 chance of that page actually showing in search results. I would also suggest getting some user generated content on the product pages. Customer reviews and comments will eventually leverage the duplicate content. Aside from that, reviews are uniquely valuable to searchers, in my opinion, they are the holy grail of content. What consumer doesn't value an actual person's opinion of a product above a carbon copied description?