Normal snakes only have one heart. Their hearts are three-chambered with two atria and one ventricle.
This heart is evolutionarily more basic than the mammalian four-chambered heart, but because of divisions and valves within the ventricle, the snake heart still functions as a four-chambered heart very similar to its mammalian counterparts.
Snakes and other reptiles have an interesting adaptation to their cardiovascular system that mammals lack. It is called the renal portal system. In this type of system blood from the animal’s tail passes through the kidneys first before returning to the general body circulation.
Learn more about snake anatomy and physiology at Peteducation.com.