Legal question from Bridge of Spies: one act, or multiple?

In the opening scene in Bridge of Spies, insurance attorney James Donovan is arguing with counsel for plaintiffs in an auto crash case. The case involves a driver of a car (insured by Donovan’s client) that hit four motorcyclists. The plaintiff is arguing that that was four separate collisions, hence four separate incidents. Donovan argues one incident - one accident that just injured four people. Since the insurance is capped “per incident”, this makes a difference in the size of the settlement.

Since I am not a law-talkin’ guy, I wonder - what IS the law in this case? Does it vary in different states?

According to a not-so-recent recent court case, when terrorists acting in concert crashed two separate planes into two separate towers, the court considered it one insurance award not two separate ones. (The difference between $350M and $700M IIRC.) But… IIRC that was a Swiss court?

Bumping for any other thoughts on this. With all the lawyers here, someone must have had a case like this. In a way, it sounds like a law school hypothetical.