Now, I've played Alpha Protocol something like 7 times but each playthrough only takes, what, 8 hours? 8-10? that's not a big deal. However, if you play a longer, more dense RPG twice it's a little bit more impressive.
tbh I don't really count new vegas because I beat that game really quickly the first time, something like 10-12 hours... or skyrim or whatever. You can beat those games in under 3 hours if you want to. Not to say you can't count them ofc.
anyway, for me it's probably either Persona 4 (2 times, total time like 150 or something) or Final Fantasy 12 (which I'm replaying now and doing all the side content, so that may turn out to be longer)