Giving you the benefit of the doubt and assuming the test gave a FALSE positive, if I was in your shoes, I would run, not walk, to two different industry-recognized drug testing companies and pay each of them do a test.
Drug test information goes into databases that can be cross-referenced and accessed years later by any number of future employers, background checkers, etc. Bad information about you that is out there, whether it is true or not, can haunt you for years.
Sure, today's drug testing company will promise your privacy. But that data already resides in at least two databases now, the testing company and the carrier. It will probably get passed on to your carrier's insurance company as well. Companies get bought and sold all the time. Company databases are prized assets. Data mining operations are regularly conducted by professionals hired for that purpose. No one can say with certainty what will happen to the drug-test-failure that now exists on you or who will see it.
The next time you change or get new health, life, disability, or auto, or liability insurance, you will be required to sign a release giving your new insurnace company the authority to check your old records. That release is all your current companies need to legally pass your test data on. A record of a failed drug test - true or not - is still a record of a failed test. While I'm happy to give you the benefit of the doubt here, insurance companies won't. If credit rating companies get their hands on the data, that could hurt you as well.
I'd be deeply troubled that the first company did not offer a retest right away. Two additional tests personally paid for by you may sound like overkill. But when you consider that a driver's entire career depends on clean drug tests, I'd leave nothing to chance.
In addition to insisting on a retest by the first company (paying for it myself if necessary), I'd get two additional companies to test me right now, so in the future when anyone researches the test data on you for this time period, the database records themselves will make the arguement that the first company produced a false positive.
Without such data showing your true clean record, people in the future may never bother to even ask you about the test you "failed." They'll make their decision based on the data alone and just pass you over and look at the next person in line.
