Same app paid for twice due to some error on Google Play Store, no receipt of failed transaction, but money deducted
As updated by OP the first payment has been cancelled after verifying in the payments Center
Since the payment had been honoured by the bank prior to the cancellation (likely), you can contact Google and talk to them and request for a refund (or from the Google Play Settings &rarr; Help and feedback)
Typical refund requests time line here