Annual leave rate after reducing weekly hours

Hi

One of our employees has reduced their hours they work - the annual leave balane/accrual is calculation correctly for the reduce hours.

However  in MYOB when using the higher of average weekly earning over the 12 months... that has increased significantly as it is based on the correct gross but the divided by the new reduced hours rather the the previous hours. So the annual leave rate is higher that it was previously. 

Ie simple example - staff members hourly rate $25 per hour and they reduce their hours from 40 per week to 20 per week.  MYOB seems to calculate the hourly rate based on prevuous 12 months as

@ 40 hours per week  - 52 weeks, 40 hours  gross $52000 = $25 per hour (52000/52weeks=$1000/40hours)

@ 20 hours per week gross still is $52000  however the hourly rate is now  $50 per hour (52000/52weeks = $1000/20hours)

So just checking this is correct? ie the annual leave hours decrease but the dollar value of the entitlement overall is the same? 

thanks