Can the tax paid per your payslips up to 28 Feb be more than tax populated per IRP5?

Is there a legitimate reason why total tax paid by the entity as at 28 February per payslip would be more than the amount stated on the IRP5?

No, the total PAYE paid for the year per your payslips should be equal to the PAYE reflected on your IRP5. It would be best to query this difference with your HR/ payroll administrator.