Thanks for posting on our community forums. Sorry to hear that you have been sent an additional sim card out, and this has caused confusion.
Remotely looking from our end, we have located your account with the details you have provided from your community profile, and can see that you have already spoken to our team this morning about getting this 2nd sim card deactivated.
Sorry to bother but that second SIM card was sent because it had updated network information and we do need to send it out to you to complete the service migration. I have sent you a private message to confirm your mobile account details.