You know why Toys R Us has a return policy like that? Because of scamming customers such as yourself who return items to Toys R' Us that they did not purchase there.

Target took money out of their cash register for an item you did not buy there, and which they may not be able to sell, which is kind of strange considering they have a similar return policy. That you spent more money there later does not make it right.

Next time sell the extra toy on ebay and use the money to buy more toys wherever you decide to shop.