http://www.591dang.com/2017/05/16/the-nintendo-account-you-tried-to-link-is-already-linked-to-another-game-account-issue-%e8%b6%85%e7%ba%a7%e9%a9%ac%e9%87%8c%e5%a5%a5%e9%85%b7%e8%b7%91/