What is the best way to tackle duplicate content, when the same product has more than one url? Is there an SEO module I can add in to better handle these using rel-canonicals for example?
how did you end up with few URLs pointing to the same product? Getting to the source of the problem will help you fix it.
Alternatively, opt for a 301 redirect and set the primary URL for Google
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I'd run a crawl in Pulno which finds duplicate content onsite. You'll need to remove redundant pages or canonicalize them. An example of unique pages report: