Help needed Carrying brick

Hi All.
Recently passed my hgv 2 and hiab
I am driving a lorry that can carry 16.5 tonne and has a hiab brick grab for a well known building firm
The lorry bed will take 14 brick pallets
The problem I have is the company from time to time want me to carry 15 packs/ pallets of brick 14 with one on top of one, I have never seen this done and have done this twice now and on the second time the pallet on top had moved. I used two straps to hold the top pallet is this safe ?