Is it permissible for me to receive the full children's education allowance from my government employer, even though my wife receives a discount for teachers at her private school and submits a receipt for the full amount, given that this does not conflict with the "duplication of benefits policy"?

The governmental entity pays the education allowance for the children to the questioner, not to his wife, and the discount is due to the wife, not the questioner. Therefore, the questioner has the right to take the full amount from his workplace and pay it to the school. Then, the school will refund to the wife, who works there, whatever portion of the fees she wishes to have refunded.