You may not know it, but the management of product URLs has evolved between version 1.6 and 1.7 of PrestaShop.
This evolution concerns the structure of the URL which always integrates the default declination on the links produced in 1.7.
PrestaShop 1.6 behavior
You had urls of this form:
Then, when you changed declination you had the url which was adapted to display the information of the selected declination:
Of course the initial url also called canonical url always displays the default declination selected when generating the product declinations.
From memory, this behavior was introduced from version 1.5 of PrestaShop in order to have a unique url by declination facilitating the sharing of product information as well as the sending of this information on price comparison sites.
PrestaShop 1.7 behavior
With the arrival of this new version, the choice was made to always integrate the information of declinations in the url of the products.
Not so good for SEO.
These urls are visible on all category listings, if you change the default declination on a product its url changes although we are still on the same product.
But, following a discussion with the members of Friends of Presta I was able to identify a simple trick to implement to return to the previous behavior and facilitate the migration between version 1.6 and 1.7 of PrestaShop in terms of SEO.
The solution to implement
To do this, simply open the file displaying the products in the listings available in your theme.
In this file you will simply replace all calls to the
by this one
Save the change and remember to clear your cache in the Performance menu
And enjoy the result.
I don't know if this will make a big difference to your search engine rankings, but in any case, this behavior is more consistent.
I have not tested on older versions of PrestaShop 1.7 so feel free to comment with your version number if it worked for you.