In my game, my partner talks to nearly all of the NPCs (and has points in Persuasion). I usually mess around or loot barrels (I have Lucky Charm) in the area. If I want to watch the dialogue, I can click on the NPC and watch what's going on. I almost never have to talk to anyone.
Just because the NPC will talk to you and repeat the dialogue, don't get hung up on that. If the journal doesn't advance or some other tangible thing happens, it's just 'chatter.'
Good luck
