Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Log into your Microsoft account on this link and check if you see two separate Microsoft 365 subscriptions listed there.
https://account.microsoft.com/services/
If there are two separate subscriptions listed, you can use the steps provided on this link to check your eligibility for a refund and to cancel the subscription you do not need.
If there is only one subscription listed, check the Billing and Payments section on your account to see if you can find the two payments listed there.
If not, try using the steps provided on this link using any Microsoft account you may have to find the second payment:
Then use the steps they provide on this link to cancel whatever that payment was for and get a refund.