OnCollisionEnter2D called several times when collision is circle

OnCollisionEnter2D only called once when Box Collision 2D made contact with another. But when I change it to Circle Collision, it called several times (call times seem depend on velocity), is that normal?

Thanks everybody.

 

Yes it's normal. The way I worked around the issue was to create a boolean flag that was checked at the beginning of the function. I set the flag to false again after the collision exit happened.