I’ve recently played through some rather old modules (AL1: Siege of Shadowdale, AL2: Crimson Tides of Tethyr, Saleron’s Gambit - Chapter One) and in all of them there was an incident were a NPC was duplicated, quite obviously not on purpose. Instead of one character as described in the story, they were identical twins (in AL1 it was the post-final boss, in AL2 it was my companion, in SG it was the town wizard’s fairy companion).
I played AL1 and AL2 with NWN Diamond and SG with NWN:EE, so the issue doesn’t seem to be dependent on the edition, neither caused nor fixed by the EE, and these are three different modules by competent authors, so I assume it’s not an in-built error either. It’s also not completely predictable, since in the case of AL2, reloading a state before the twin popped up helped me to get rid of it (at least on the second try), so it seems like there’s a certain chance of this to happen but no guarantee.
Has that ever happened to others here as well? Is it a known issue with older, e.g. pre-1.69 modules? Or a glitch in NWN in general?