Perhaps I misread the question. I inferred from the question that it was only one offensive player in the first spot, thus one simultaneous violation -- one on the offense for occupying the first spot; one on the defense for failing to occupy that spot.

If both first spots were occupied by offensive players, then you have two simultaneous violations. But the outcome is the same either way.

Not true.

Without getting into the semantics about whether it's "one" or "two" violations, it's the same whether A occupies one or both of the lower spots.