Discounts provided by gifts, punch cards, or deals can be applied multiple times to the same purchase. Suppose you have a "Buy 1, Get 1 Free" deal for coffee. If there are 2 coffees in the shopping cart, 1 of them will be free. If there are 4 coffees, 2 will be free. And so on.
From the discount configurations when creating deals or gifts in your Campaign Center, you can limit the number of times each discount can be applied to the same purchase.
For the "Buy 1, Get 1 Free" example, this means that if the limit is 2 and there are 6 coffees in the cart, only 2 will be free.