Some retailers permit exchanges with another identical item.
These are most often provided where a buyer has made a mistake in an item's size or color. You return the item and receive a credit slip or memo that allows you to apply the amount you paid toward other purchases in their store. We see this often when the customer has no sales slip or proof of purchase. Many items are seasonal and cannot be resold if returned after too long a delay. But this is also a policy, not a law.