Why is the advantage of having four chambered heart ?

Explanation

The blood circulation in human heart is called double circulation because the blood passes thruogh the heart twice during one complete cardiac cycle of the body.
Once through the right ventricle to the left auricle of the heart , i.e., pulmonary circulation. Second thruogh the left ventricle to the right auricle of the heart viz , body tissues, i.e., systemic circulation.