Log into any Microsoft account you may have on this link and check if you have more than one subscription:
https://account.microsoft.com/services/
If you find more than one subscription associated to your account(s), you can use the steps provided on this link to check your eligibility for a refund and to cancel the subscription, you should also disable any recurring billing on any subscription, except the one you want to keep.
If you are unable to find more than one subscription on any Microsoft account you may have, go to the Payments and Billing section, are you able to find extra payments listed on your account(s) indicating you have more than one subscription.