https://www.consumer.ftc.gov/articles/0181-unordered-merchan...
Q. Am I obligated to return or pay for merchandise I never ordered? A. No. If you receive merchandise that you didn’t order, you have a legal right to keep it as a free gift.
Q. Am I obligated to return or pay for merchandise I never ordered? A. No. If you receive merchandise that you didn’t order, you have a legal right to keep it as a free gift.
You don't have to send unsolicited goods back or even notify the sender.
But duplicate orders don't count as "unsolicited" and should be returned - however "there should be no cost or inconvenience to you" which is where Nintendo fail badly here.
Cool, so OP could take Nintendo to court to recover lost wages!