A square wave bolus gives you insulin at a steady rate over the time of the square wave, thus if you had a square wave over 2 hours and bolused 4 units, it would administer 2 units/hr over the 2 hours. A dual wave combines a square wave bolus with a regular bolus, giving you an initial bolus all at once and then spreading the rest out as a square wave.
I am not sure what your doctor mean about a 25% square wave. Typically with a square wave, you set the amount of the bolus and the time over which it should act. In the case of a Dual wave, you set the total bolus amount and then set the amount/percentage of the bolus to be administer "now" and then you set the amount of time to administer the remainder as a square wave bolus. It may be that your doctor was referring to a dual wave, but you need to confirm this.