How's Hawaii? I wonder if the lookers are Simulacrums of another slave race. On that thought, it's redundant to have two monsters that are functionally the same, but if the immitation BoB is more interesting than your alien equivalent, you know you made a boring enemy design. in M2 the lookers get replaced with Ticks, Wasps with Drones, and Hulks with F'lickta. They also redesigned pfhor fighters because they were so self-conscious about the clown nose, and gave us pfhor ships in all the colors of a circus tent
Hawaii is great! Thanks for asking. I have thought that perhaps the simulacrums were able to be made with the help of the Lookers since they are similar. Who knows, but it's a fun theory. There were a lot of redesigns in Marathon 2 that helped the game get quite a bit better on the most part.
I figure the Durandal[Tycho] could be in reference to the reconstructed Tycho from Durandal's image... she can no longer tell them apart, hence Leela's confusion. Everything is not as it seems could be another foreshadowing to simulacrums but that's a stretch. Lookers make their first appearance here? If you asked me on the spot what's the first map with Lookers I would guess something sooner than Map12. Is the reactor about to blow? Maybe Fire! Fire! Fire! is the aftermath of this.