Notice how juxtaposition and editing work in different ways when you compare the first and second scene:

1) 0:24 to 0:39 – Same camera viewpoint; juxtaposition of two characters onto one body

2) 0:40 to 2:02 – Switching between camera angles and edits to generate the impression that two characters existing in two separate bodies are talking to each other, though there never is a shot in which both bodies are juxtaposed. That juxtaposition is mental.

3) 2:03-2:04 – Notice, too, how there is only Smeagol but not Gollum. More importantly, notice how the perspective switches from Smeagol positioned to the right-hand side back to Smeagol on the left-hand side front. We return to the original camera viewpoint at 0:24, but now one character inhabits one body.

To enjoy the video even more, follow the Smeagol-Gollum conversation in the fan-reproduced script found here.

What’s interesting here is the cinematic marriage or juxtaposition of form and content. Smeagol-Gollum appears as unitary, two manifestations of one creature; but a deep chasm—out of years of solitary obsession with the One Ring—exists between the two. From the  viewer's point of view, one who is familiar with the Lord of the Rings (LotR) world, the scene is a truly delightful. It is even more revealing for a viewer not familiar with the character of SmeaGollum. The juxtaposition at 0:39-0:40 reveals two types of switching:

1. Switching content within the same viewpoint, and
   
2. Switching viewpoints

This delivers a two-pack punch, an achievement of formal cinematic production and of cinematic adaptation of one of the most beloved/reviled/memorable characters in LotR.

One more juxtaposition occurs—of motion capture with traditional animation. In this video, you see Andy Serkis, the actor whose motions and voice animated Smeagol-Gollum, in his motion capture suit, juxtaposed with the final, completely rendered SmeaGollum.