Can add item multiple times even with qty=1

(URL) hennashoppe.com/products/web-shoppe/webshoppe-clothing

HikaShop Essential: 2.2.1
Joomla! 2.5.14 Stable
PHP v5.2.17
Chrome Version 29.0.1547.66 m (broken)
Internet Explorer 8 (broken)

Hello,

A beta test found what appears to be a weird bug in the cart system.

All of our items are hand made, so we sell a lot of "1 off" pieces. In this case, if a customer adds the item once from the category listing page, and then adds that same product from the product listing page, the item will appear twice in their cart. I haven't verified if I can actually complete check out this way, but the items should not appear as two separate line items regardless.

Example:
1) Enter "1" and add the first green skirt to your cart on this page: hennashoppe.com/products/web-shoppe/webshoppe-clothing
2) Click on the same green skirt and click add to cart from the product page: hennashoppe.com/products/web-shoppe/webs...yellow-tribal-design

Click on the cart icon at the top (or check out form the left) and you'll see both items entered into the cart despite there's only quantity=1

Note that attempting to increase the quantity from the check out page correctly generates an error.
Note that attempting to add >1 from the category listing page will say successfully added, but the cart will correctly only display 1 item.

Hi,
Firstly can you show me a screenshots of your product configuration page ? Also, can you download the last Hikashop version through our website, install it, and test it again ?
Thank you.