This will most likely get your robot banned because they will consider both pieces as one piece with a larger thickness than allowed.
What is usually done is to drill both pieces of polycarbonate and screw them together using a spacer or a washer in between, this allows their use to be legal and count as independent pieces.
It should be noted that if you use this method, although the limitations of polycarbonate area to use are not very large with each layer you are doubling the area of the same.