In WooCommerce Marketplace Reward System, if the admin has enabled the “multiple reward condition” in reward settings then the reward system will work for both product reward and cart reward.
If there are reward points available for a product and the product price also lies in the cart reward category then the buyer will get the reward points for both product and the cart. e.g. if the reward points value for the product is 2 and the reward points value for the cart is 3 then the buyer will get 2+3=5 reward points for that transaction.
Please follow the user guide for more information WooCommerce-Marketplace-Reward-System