Register mortgage

suppose a borrower has mortgage his land through register mortgage due to technical mistake of bank noc has been issued . Bank is again having the right to mortgage that land again or not if bank is having than how bank can proceed for mortgage . 2. if the loan has disbursed and borrower is denying for the mortgage some disbursement is already there than how bank can mortgage if mortgage deed is available in register mortgage still the borrower is having due with the bank