INTEREST ON GST TAKEN TWICE BY MISTAKE

IF A REGISTERED PERSON FILES HIS RETURN SHOWING HIS INPUT TAX CREDIT TWICE (GSTR 3B ) SUBSEQUENTLY THE REGISTERED PERSON FINDS OUT THE DUPLICATION , WHAT WILL BE THE CONSEQUENCES UNDER  GST ACT HE HAVE TO PAY INTEREST FOR THE EXCESS CREDIT CLAIMED(BUT NOT UTILIZED) IN HIS RETURN. IF INTEREST IS PAYABLE AT WHICH PERCENT - 24% OR 18% AND FROM WHICH DATE HE HAVE TO CALCULATE THE INTEREST.