I think you're on the right track with your theory, but I think it's more metaphorical than literal. Al1 and Fortress aren't actually the same person with a split personality, but from the perspective of being a random, faceless 'man at the shouting box', they might as well be. And, from a meta perspective, you could say the same about Adam Butcher himself, or even you, or any of us.
I don't think the theory that Fortress and Al1 are the same person is that plausible, if for no other reason than the Welsh police in the article state there are two sets of footprints and signs of a struggle
