Apparently, you can only return items without receipts twice from your registry, period. And your limit is $150 per time.
We registered in December right before christmas and my mom bought us some items for the bathroom. One item was damaged when we recieved it in January. When returning the item, they told me this would be 1 out of 2 times I could return anything from the registry OR I had to call and get the credit card number the item was purchased with.
They wouldn't just do an equal exchange. In addition, they were already discontinuing the colors we chose for our bathroom towels.
Since most guests don't include receipts in the wrapped gifts and it's pretty rude to call each one and get their credit card number, we took all our registry off Target and registered at Bed, Bath, and Beyond and Amazon.com. Much better at those outlets.