How is duplicate content made "for users"? Why would I want to find exactly the same prose in multiple places?
* Product with a category name in url, or without, or under multiple categories
Both are very useful for humans, but have to be massaged with canonical urls to please Google machines
I don't see how the same product under a variety of URLs, one for each category it's in, is at all useful to me as a human. It actually rather annoys me when the same page has a whole bunch of URLs: I can't tell which is the "real" one, my address bar frecency gets messed up, visited links don't work correctly, etc.
As a consumer, if I came to the website looking for instructions on how to use my [Deluxe] Widget, I would reasonably expect to find the same operating guide on both product pages.