A dual braking system means that the braking system is divided into two independent parts. The way ABS works increases safety and is available on most cars except older models.
Today's cars have hydraulic brakes. This means that braking force is applied from the pedal to the brakes by means of a brake fluid.
ABS allows a car to brake and still maintain control of the steering.
For in a depth look at how ABS braking works click here >