The dual-channel videos of Doppelgänger are projected to translucent screens that can be viewed from either side. Two threads of sci-fi narratives occur in parallel and yet are light years apart. In the work, upon the launch of a spacecraft, another spacecraft launches in a parallel universe as well. A lone astronaut named Alice is teleported to the spacecraft bound to another planet. Yet, due to an unknown reason, she and her spacecraft Hermes II return unexpectedly. Appearing unsuccessful, Alice has essentially created a new doppelgänger in another universe, who encounters a world opposite to hers. In the first reality, she returns to Earth, received with warm welcome and care. Nevertheless, in the second reality that accidently occurred, she was deemed as an alien that poses a threat. The two different universes are interwoven and mirrored in a dual-channel video in sync. This work, pursuant to the dialectics on the nature of moving image medium that Douglas has been excelled at, fuses the dual-channel and viewing from both sides into the threads of retro sci-fi image narrative.