Hi,
It's not duplicate meta description then, it's "duplicate content" that google tells you.
Having two URLs to go to the same page is quite normal and not really a problem.
The issue is that in that case, you want to have a canonical URL in your meta data in order to tell google which one is the main one. If you don't, or if you have several canonical URLs for a page, you'll get that error.
HikaShop adds its own (correct) canonical URL if you tell it to.
However, on some websites, it seems that there is a bug with the system SEF plugin of Joomla which adds its own (incorrect) canonical URL to HikaShop pages and thus you get that error.
The simplest in that case is to deactivate that system SEF plugin. It should not impact the rest of the website and should fix that issue with google seeing two canonical URLs for the product pages.