OpenCart is a great e-commerce package, but its default link scheme leaves quite a bit to be desired. Install OpenCart, carefully add all of your products with their associated descriptions and images. Make your template pages pretty, add your brands, put together your category pages and so on. Pretty soon, you’ll find yourself on the receiving end of an SEO mess destroying any chance you have at ranking well for your keywords on Google.
I, like thousands of other OpenCart users, faced a similar problem when setting up a store for a client. Seeing a need for a simple solution, I developed an easy inexpensive vqmod plugin for OpenCart that will solve this problem within minutes.
OpenCart SEO Link De-duplicator installs easily, and once installed will not only standardize your links across your site (i.e. the same product link from a manufacturer page, the home page, and a category page will all have the same URL), it goes one step further, 301 redirecting all the duplicate page links to the correct, canonical URL.
Hope this helps somebody facing a similar problem.