Is Polybag still required for boxed liquids?

Hi All. Just preparing my first shipment. Each item is a small box containing two 250ml plastic bottles containing shampoo. Each bottle is secured with a firm screwcap, but I have applied my own cellotape seal as this is a product manufactured at home by myself, and i don’t have the equipment for a heat applied plastic double seal.

The two bottles are then securely packed in a box which also contains bubble wrap to reduce movement during transit. It is pretty secure.

My question is whether I should still place the bottles in poly bags, inside the box?

I have read all the FBA packaging advice, but it seems to refer to poly bags when the items are not in a box as in my case. I cant find a clear cut explanation of what i need to do do. For instance, I presume the drop test will consist of the warehouse staff dropping the box as opposed to dropping the items inside the box? How will they know if there is a leak straight away unless they break open the box to check the contents inside.

I am happy to poly wrap , but just dont want to over pack if not required, as the costs all add up eventually

Many thanks for any advice