That's called a Mid Eye leaf springs. The feature is used to lower the car without loosing too much free arch. Used in many other performance leaf springs for years. Leaf springs are offered in Reverse Eye also.
This is the front leaf pack on a Hothckis handling leaf spring. They have two thick supporting leafs that go to the eye. Then there is a special leaf on top of the main leaf, that is to control axle hop under heavy braking. So they are special compared to a MP Super Stock drag race spring.