Cashing out annual leave and PAYG

Hi, I need to pay out an employee for 14 days of unused annual leave. I have followed the MYOB instructions for cashing out annual leave https://www.myob.com/au/support/myob-business/payroll/leave-and-entitlements/managing-your-employees-leave/cashing-out-annual-leave 

When I do an unscheduled pay run to pay the cashed out leave separately, the calculated PAYG Withholding is lower (and they therefore end up with a higher net pay) than if I was to add the equivalent amount owing to their normal monthly pay run as a 'bonus'. Which is correct?