Shivering Isles, but that was like a Shadow Link sort of thing, no dialog or anything.

Goes to fight evil clone dies instantly. Admits defeat because your to powerful.

Tells curie to kill evil clone , she kills it in one hit then dances on top of your evil clone or was that you I'm confused .

What if... our protagonist is actually a Synth and was replaced when he/she was completely unaware.

Then because of the natural badassery, the real one broke out of the wherever Synth-making lab is and approach you and tries to kill you.

And so now you'll have to find and kill the real you before they managed to kill you and it won't be in 'boss battle' approach.

And the way they are trying to kill you will be the same as how you most of the time kill your enemies.

And the original Protagonist may send settlers as scouts, armed with heavy firearms.

I'll be f*cked. Yeah.