Three points:
1. Numbers are handled in a different part of the brain, and are treated as different concepts. A six and and a nine, for instance, are the same image, but they are not the same number. When numbers are handled in the same way as images, that's called "dyslexia".
2. We are discussing testing the possibility of telepathy. Isn't it rather odd to be accepting, for the sake of argument, that telepathy exists, yet rejecting the possibility that numbers are treated differently from images?