I have an issue with extra items/duplicate items being added to the shopping cart.
If a user adds an item to their cart, then goes to another page, then uses the browsers back button, an extra item gets added to the cart. It appears to be happening in ie9 and firefox 14.0.1.
the issue doesn't occur in webkit browsers such as (google chrome, safari, mobile safarid) and opera (newest versions tested).
recreate issue: go to a shop page > click add to cart button > go to new page > use browser back button
Browsers affected: ie9 (possibly older version), and firefox 14.0.1. (mac osx and windows)