As MrX pointed out, it is the current fad to put red and green LEDs into a fixture and is for aesthetic purposes only. Adding red and green does not, in and of itself, make a fixture "full spectrum" regardless of what the marketing folk are shoving in your face this week.
White light is full spectrum, to some extent or another. Don't believe? Hold a prism up to one of your white LEDs.
Be aware that the red and green LEDs can be quite overbearing and should be used very sparingly with wide angle optics and, IMO
, always on their own dimming channel. They, of course, make red look more red and green look more green. This doesn't mean the corals are actively using the light, it means it is being reflected so YOU can see it. In other words, a red object is red because that is the color spectrum it absorbs the least and the spectrum is being reflected, therefore you see a red object. They can also make other colors, and your whole tank, look like puke if you use too much.