LOL - this again.
Here is some free advice. Forget about trying to 'game' the test.
You *MAY* get away with it once. Twice is extremely unlikely, and three times... well, I've never seen anyone pull it off, mostly because the guys administering the tests can tell you're fucking with the results, so they'll make the next one without any notice or privacy.
Instead, admit you have a problem and get into the therapy they require. Failing that, get a job where it doesn't matter and you don't have to take tests.
Unfortunately, only 1 person in 20 will ever go clean and stay that way.