My friends got their save data on all of their games replaced by mine after netplay

[ArrowT0DaKnee]

We were playing Mario Party 7 over netplay and we finished the game. I was tired and wanted to sleep so I ended the netplay. One of my friends sent me a message saying that all of their save data on their games was replaced by mine. All of their miis has also been replaced by my miis on the mii channel. I never shared any files with them, nor did i share my bios.