Canonical does not work/ bad for SEO?

Hi

At the moment I use the free version of “Premmerce Permalink Manager for WooCommerce”. In the beginning I thougt it works fine. The pages are dublicated with the right url-structure, but in google index are as well “domain.com/product/…” as “domain.com/(individual.category)/…”. Is that a problem? I use yoast Seo and can’t find the canonical tag on the old pages. To me that looks like the plugin just duplicated the pages and thats it. That would be a big problem for google.
Hope you can help me ??

best regards
Daniel