Second opinion for what? The only opinion that matters is St. Lukes (not loots). If people are trying to think it's a money grab, it's not. You pay 1 fee for medical. It covers sputum as well. Now they have way more work to do and they do not get any more money.
I think it is due to poor equipment or poor training on how to read an x-ray. Sadly my wife was flagged and had to go through this and it really does suck. By the time she finished and we got a new interview date, her visa was set to expire a few days later. Appointments at the embassy were tough to get because it was during covid. We ended up having to do the medical again. 2nd time x-ray was fine and no sputum.
Like I said, it sucks, but you will make it through.