I am trying to fix the problem in uc_product_kit 5.x-1.2 where the same kits are added as individual products if you hit the 'Add to cart' button twice. See issue #289102 for more information.
It took me a while to figure out how uc_product_kit saved what product kits were added to the cart. I discovered this data was serialised and saved in DB table uc_order_products in the 'data' column. In the module itself it is present as $data (in this case I'm looking at uc_cart_add_item()). During this search I discovered that those kits were added as individual products because when trying to select an existing kit from the cart the DB couldn't find a match against $data, I believe (primarily) because $data['unique_id'] is not always being saved tot the DB and when it is, it is unique, so it will never match any product.
If you would be so kind, I'd like to have some confirmation on this and more information on what $data['unique_id'] does exactly and if it is necessary. For a project I'm working on I need products to be listed only once in the cart and uc_cart_add_item() probably is one of two parts in the code where things go wrong.
