So i figured out a way to do the long distance talk glitch, and it seems like it related to character positioning.
If you try to talk to someone while on a slope, you might start moving slightly. If you slightly move, you can do the glitch. Repeatedly talk to a character until you start sliding and don't finish the conversation until you're out of their normal talk range. Finish the conversation and you should be able to talk to them from a distance.
You should be able to end the glitch by getting near the glitched npc and talking to them.
If you try to talk to another character while the glitch is still active, their text repeats too. You can spread the glitch to every character on the map and eventually the text box will be an unfixable mess.