Being that you disclosed that you had synthetic urine, the doctor put in the comment section for the lab to test the urine if it were synthetic or real. The MRO wrote in his report that the urine specimen was negative but it was synthetic urine. Yes they can test for it. And your potential employer was notified of it.
Don't blame the doctor, the lab, the MRO or the potential employer. There is only one person to blame, yourself.
Let me ask, you said distribution. Are you a commercial driver? If so, the state may also be notified about the failed drug test. And being that they tested for synthetic urine and it was confirmed, it would be labeled a failed drug test.

