Three samples will end any questions wrote:
This is why there should always be three samples and all three get tested. Simple best of three is the result. I wonder how many A samples that are negative would have B samples that are positive? We'll never know, of course, because once the A is negative the B gets destroyed. Take an A, B, and C and if you fail two you are banned.
This is dumb. You are trying to make the testing process more complicated than it needs to be.