Biryani is love in Pakistan for most of the people, they are crazy about Biryani, I know many people who eat Biryani in lunch on daily basis, this is so crazy. So just imagine the value of Biryani in Pakistan. Here we have single and double plate, double plate means two pieces of beef/mutton/chicken with more rice so I think you ordered double plate.
As per the name of the restaurant, Hyderabadi people cook different type of Biryani which is called Kacche Gosht ki Biryani, I am not sure why they call it so but it means half cooked meat Biryani. Also they have many other delicious dishes so I recommend to try some other dishes too when you visit this place next time.