Is there a max angle at which two lasers could pass through the pupil and strike the retina? That's assuming that strikes elsewhere don't pose a blinding risk for the energy level required to kill a mosquito, which I have absolutely no support for. But if that is the case, you could place your lasers and define a kill zone where no two can converge with less than a safe angle.

If the assumption isn't correct, you could possibly still place at least two lasers and define a narrow zone between them where the angle would be about 180 degrees. Would be damned tough to hit an eye from two sides at once. But that limits you to half power per laser, which probably isn't enough margin.

We are talking about two different safety issues:

(1) Targeting the wrong thing.

(2) Even if the targeting is correct, missing by a small amount, or running the laser for slightly too long, and hitting something else by mistake.

If the lasers converge for full flux, the risks associated with (2) are better managed, but that doesn't speak to (1).