It is better to have unique description for each product.
Thanks & Regards
MS Web Designer Team
Official Shopify Expert and Partner
Not really. You might offend Google and how it treats duplicate content thereby diminishing ranking of all your products.
If your products are all the same and vary by some parameter such as colour, size or similar, use product variants. If your products are generally of the same type but do not fit the variant paradigm, then try to use combinations of descriptive content - say having a set of a dozen product property descriptions each with 2 variations. Product A would be described as Content Property 1-1, Content Property 3-1 and Content Property 5-1, Product B would be described as Content Property 1-2, Content Property 3-1 and Content Property 6-2 etc etc. That way you'd have plenty of choices for your descriptions and repeating one fragment won't hurt as long as the others are unique.