In regards to the duplicate content, then just add a noindex meta tag to one of them, or block it through robots.txt, so the search engines can only see one of the pages. You only need 1 to rank so its not a problem.
With regards to the product id, you are correct in that the name of the product in the URL is much better in terms of
seo than just the ID number. It suggests your developer doesn't know how to do it!
It's actually very easy, and you can do it in a number of ways:
Tack on the product code to the end of the product name eg ipod_nano_2431, then with the code you can easily extract the product id.
Alternatively, you can use rules using Apache's mod_rewrite module to achieve the same thing.