I have a habit of attempting to break into a sprint from the crouched position. In the mod, double tapping the movement key while crouched regularly makes you UN-crouch and begin sprinting.
I have noticed that doing this while stationary and crouched does absolutely nothing. Attempting this while crouched and already moving in a certain direction will result in your character moving in that direction until you let go of the movement key that was double-tapped.