Hi,
You have to create a menu of the type products listing which allow to reach all the product, so select the main category and allow all the elements.
Then in Configuration > Features > SEF, select "Use canonical if specified" for the option "Force canonical URLs on listings" and set a canonical url for your products. This way all the url will take the product canonical url, and will be the same.
You can too select to generate the canonical url automatically if required, this way when you reach a product page from a menu, this will take this url and set it as the canonical one.