I did.
The error confuses me, too, as it happened whenever I engaged that Pirate battlegroup with just the Buffalo II, the Lasher and the Hound. The battle would start, then as soon as one ship got on my sensors, bam, fatal error about duplicate demolisher hulls. Which...makes no sense as there's not even a Demolisher *in* the battle.
I'll try making yet another new game and see if I can replicate the bug again. This time, I'll attach my whole log file.
EDIT: New game started(I had nuked my saves again to see if the older 1.5E save was causing problems), started with a Lasher. Engaged...I think it was a Pirate Scout with another Lasher frigate and defeated it in combat. No crash. Gonna' see if I can snag a Raiders fleet.
EDIT2: Snagged a Pirate Raiders fleet with a lone Scarab Autopulse, and waxed it. Still no crash. Starting to think that maybe nuking the saves is what fixed it, though I can't imagine why that'd be since it shouldn't have loaded any save but the one I made with this version.