Hi,
i don't use yet ps 1.7 in production so i am not very skilled i just tried only the 1.7.1 v and stil has too many bugs, anyway,
in your tpl file looks like there is a hook that "could" duplicate the add to cart button of the classic theme product.tpl:
{block name='product_add_to_cart'} {include file='catalog/_partials/
product-add-to-cart.tpl'} {/block} {hook h='displayProductButtons' product=$product}
You can try remove the hook.