Quantities on packing slips

[4erika]

I have a problem when customers add something to their cart, and then decide later that they want to add more of that item. If they don't go to the cart and edit the quantity, and instead just click on the item on the website and add more, it duplicates the item on the packing slip...which makes me wonder if they accidentally ordered the item twice by mistake or if they just needed to order more of that item. Is there a way to tell the cart to just increase the quantity of the item if someone puts that same item into their cart instead of creating another line item in the cart?

[ShopSite David]

Do the products that have separate line items have order options? If so, ShopSite does not combine them into one product with a quantity of two, in part, because the shopper may want to change the order option when it is displayed in the cart.