Common breakfast specials at McDonald's priced at two for $3 generally cover selecting any two items from a narrowed list, often including a large drink, a breakfast biscuit or breakfast McMuffin, without prohibiting selecting the same item twice. For example, two sausage egg biscuits for $3 is a common promotion.
Generally, the two for $3 special at McDonald's lists one to three menu items from which to assemble the combination of two items to arrive at the $3 price. If the special covers large drinks, sausage McMuffins, and sausage biscuits, since any combination would be valid, one could hypothetically order two large drinks for $3, two sausage McMuffins for $3, two sausage biscuits for $3 or any combination of two different items from the list of three for $3. McDonald's often initiates this breakfast promotion if there is a new variation on a McMuffin or biscuit sandwich available, so that the promotion can include the new variation to allow customers to try the new product and to boost sales of the new product.