All inventory filled by Amazon (almost all prime goods are filled this way) is commingled by sku. This allows amazon to distribute the items across warehouses a

All inventory filled by Amazon (almost all prime goods are filled this way) is commingled by sku. This allows amazon to distribute the items across warehouses and give faster delivery times. Problem comes when another seller claims to sell the same item. They send their fake items in marked as the real thing. They get mixed with all the real ones. Now when an order is placed from legitimate seller it can be filled using fake inventory.