Although it is maximum 4 per household, you can order them one at a time, and Tesco will track how many you've already ordered. This means that you can put four seperate requests through, and if you click through Quidoc each time, they should track seperately.
I use a different cashback site and I managed to get 4 seperately tracked 'transactions' i.e. 4x as much cashback as if you ordered all 4 in one go