If it serves the story I'll retract the criticism. If it were to involve the Engineers experimenting on David, I could go for it a bit, but I don't much like the idea of a rescue mission with two or more Davids scheming, etc. Why not have multiple types of androids? I just happen to read it cynically at this point. "People liked Fassbender, let's have two of him!"
Ripley 8 and 7 was a good scene, but that's just it: it was one emotionally involved scene that added to the plot. That was also 17 years ago and I have no faith in the studios to not just Fassbender wank the whole movie. I can somewhat say "I'll have to wait and see," but it's not an aspect that has me very excited.
But since we seem to just fundamentally disagree, I've said all I have to say on the issue.