If an item belongs to multiple discount groups that you created, the app will follow the behavior you specified in the "Settings."
Apply newest group: This will use the newest discount group for the entire order.
Apply oldest group: This will use the oldest discount group for the entire order.
Apply greatest discount: This will go through the customer's cart on an item-by-item basis and use the discount group on that item that gives the greatest discount.
In this example, a customer is tagged with discount groups "cart" and "line". The behavior is set to "Apply greatest discount."
Upon checkout, the discount applied is the discount group with the tag "line" because it will provide the greatest discount.
Please note that it is not possible to apply more than one discount to a single product.