I'm drinking that strip NC from GNC that I had bought (and now can't return) before I read so much about how it's a scam in the unlikely case they tell me they know my sample was a synthetic and make me pee in a cup right then. This doesn't happen, though, does it?
If a urine sample is ruled "not consistent with human urine", it is considered a "refusal to test" under DHHS regulations. That means a retest is not an option.

However, if an employer had somehow taken a liking to you for one reason or another, s/he may opt to have you take another test using a different facility (non-DOT situations only).