Lucknow University — Refund of enrolment fees

I have taken admission in Ph.D program[protected], and have paid entrolment fees during the time of fees submission date13/12/20. But gain on 18/9/21 I have paid for the entrolment fees on enquring from the office, i was informed that if it was already paid then payment should be rejected but it was not payment was succesfull and have got the receipt, so i want to refund my second payment of entrolment fees . Kindly see to it and help me out .