isabelc/WooCommerce-Max-Quantity — pull request #1 by thekillerdev (2014-02-27 20:10:14+00:00)
Title: Update woocommerce-max-quantity.php

It was blocking items from being added to the cart and not actually caring about the variation ID.
Now it checks for the product_id plus the variation_id to see if it's already in the cart.