Card charge

If Card B is your back up payment it may not have been able to charge card A so it charged Card B

When you purchase a subscription it's set to automatically renew and the charge is run as a recurring or pre-authorized charge. Rarely credit cards, some debit cards and MOST prepaid debit cards will not allow pre-authorized charges. You can contact your
bank and ask them to allow pre-authorized charges on that card, if they say no you will have to use a different card.

Hi, I hope you're doing great out there. I am an Independent advisor and I am here to help you in regard to your concern.

Do you previously subscribed to Xbox Game Pass Ultimate for your PC or Xbox console? If yes, kindly check all Microsoft’s account that you own and sign in to https://account.microsoft.com/services and check if this is from a renewal of your subscription.

Also, please check all of your Microsoft’s order history via https://account.microsoft.com/billing/orders.

You can request a refund by signing in to https://xbox.com/refunds.

Not exactly sure how it works. In my case I used a credit card with a zero balance. They did charge the card but on my credit card online statement the card showed the charge but I still had a zero balance. Now the charge has been taken off the card like
they said. Hope this helps. Good luck.

Contact the card issuer and ask if they have any blocked charges on the card. Don't ask if the card is good, ask them to specifically check the activity and see if there's rejected charges.