This is my response to Kaitlin Pendley's posting. I put it in a new post so I could post a video.
I personally don't think this voice-over does this scene any justice. It clears up the ambivalence but does so a little too much. I imagine Ridley Scott intended the film to be ambiguous and the voice-overs take away that element. So, I agree with you that the voice-overs seem to be geared toward an unperceptive audience. I think this scene is powerful enough in itself. The emotion-driven staring contest and heart-to-heart spills do enough to illustrate what you point out as the "commonalities between humans and replicants." Here's the version I prefer. Around 1:50 in this video, you see the screen fade form a close-up on Deckard's face to a close up on Roy's. I think this is a very blunt illustration of the sameness of Deckard and Roy despite their being either humans or replicants.
Well, I can't get the video to work for some reason but here's the link: