I've done it myself a couple times on youth bows that came out way too light. But i put the other layer of glass on the back of the limbs. I used .030 glass and sanded the working portion to bring it back down a bit.
i had issues with doing it on the belly side one time experimenting with a glass power wedge overlay on one of my prototype bows. I feathered out the glass to the fade tips using epoxy. Came out looking good, kicked up the draw weight and eliminated the hinge i had going.....but.... It started to lift a couple years later after about 5000 arrows. I loved that bow.... Kirk