Confused About A Few of the Characters (Spoilers)

I just watched this film. I had a lot of issues with it, but I'll save that for a review. My question is this - who was the guy in the pig mask vs. the other guy that was there when David delivered James? I didn't pay that close attention to faces or outfits (frankly, I was just trying to get through the film) but I assume the guy in the pig mask was Damien. I didn't think the other guy without the mask could also be Damien because he couldn't be in two places at once (and at that time, pig mask guy was running after the two girls). And we know that Damien is disfigured (we assume that's the reason for the mask). Also, was the guy that snuck up on Kyle in the cemetery that same guy in question who was with David and James, or was this someone else?