Lots of missing information here.
In what country? In some countries sales can be made by third party vendors over which Apple has no control. You need to talk to the vendor.
If this was a sale made through Apple, have you asked for a refund? I am kind of surprised you even could subscribe to something twice if you are using the same account. On the other hand, I have zero familiarity with that app.
Review the information in this support article by clicking on the link to learn how to cancel a subscription from Apple. ➔ If you want to cancel a subscription from Apple - Apple Support
If you subscribed to this directly with a third party, see: About purchases not billed through the App Store or the App Store’s In-App Purchase system - Apple Support instead. You need to work directly with the vendor, not Apple.
If you wish to pursue a refund, follow the directions in this support article about how to request a refund for apps or content that you bought from Apple ➔ Request a refund for apps or content that you bought from Apple - Apple Support Note that Apple states that “All transactions are final” and while you can request a refund you won’t necessarily get one.
Read this support article for information about how long it takes to receive a refund (if one is granted), and how to check the status of a refund for apps or content that you bought from Apple --> Check the status of a refund for apps or content that you bought from Apple - Apple Support