I am using Oscommerce v2.2 RC1 with the Google Checkout Module v1.4.5 with CCS from Ropu written on 2 Oct 2007 at [url removed, login to view] I used zone rate shipping based on the weight of the item.
Everything works fine except the merchant calculated shipping in Google Checkout will not calculate weight for the same item with the different attribute. For example, if I buy 2 boxing gloves (1.2 kg each) red color and black color, it should weight 2.4 kgs but the google checkout will calculate based on 1.2 kg only one gloves.
I try install the fresh unmodified OSC with this contribution and it has the same problem so it is not because of my modification.
I clone my website to another host which you can get the access on my clone host and fix that one. You can check my clone one at www.monavie-thailand.com. You can try add same products with the same attribute. The OSC will calculate correctly but Google checkout will calculate the weight only one product and ignore the attribute.
You can also check my OSC backend at [url removed, login to view] My login is admin and my password is testtest Please let me know if you need any information.