I've been using the clear blue dual hormone kit. I've been sceptical about why a new tester is needed everytime. Does it have some sort of memory? is it just so we spend more money? Etc Today is the first day of testing for this month, so I decided to try both the new tester and the old tester with the one pee. One test showed a flashing face and one showed the blank circle. How can this be possible when the stick is detecting the same hormone from the same flow of pee???