For all who have not read what this man wrote in FAQ recall here ...
A string beginning with “?cPath” is being added to the end of a product's URI.

The module retains Zen Cart's category history when linking to a linked product which is not within its “master” category, so the full path back through any parent categories is available. To do so, it is essential that the “cpath” query string parameter is added to the URI.

Without this feature all linked products would always show as belonging to their “master” category, which will not be the category the customer has accessed the product from.. this would make it appear to the customer that they had “jumped” to another part of the site, they would no longer be in the same category they were in previously!

There is no way to avoid the cPath parameter being added for linked products. It's advised to use linked products only when necessary and/or to simply accept that it's not possible in Zen Cart to omit the cPath parameter in the URI of linked products.
I am in the same situation as you with products that have cpath followed by number and Google say that i products with the same title and description duplicate.
I read the FAQ by Ceon and I understand you can not deal with this shortcoming.
I apologize for poor English. Thanks!