In Act I (at least, haven't checked Act II), Gareth and Exter are duplicated and only one has a weapon and working combat AI (but not the one with the weapon RIP).
When conversing with these duplicate characters, it always focuses on a particular one (which sometimes sends the camera into the abyss when they're not close enough).
It's especially annoying with Gareth, because if you discover his initial battle but don't start that combat immediately, he will likely die.
Not really game breaking, but still quite annoying. Hope you have a big enough boot to squash this bug