Double cab pick ups normally have a front passenger area with a second set of seats along with 4 doors which can be opened irrespective of each other and an uncovered pick-up area at the back of the vehicle. In many cases, if the payload is 1 tonne (1000 Kg) or more, then it would be classified as a van which will be used to carry goods.
You can have a private double cab insurance policy if your vehicle meets certain strict requirements and you are going to use it only for Social, Domestic and Pleasure purposes. However if the vehicle was designed primarily for carrying goods, then you would need to get a commercial insurance policy for it.
