Tin Man

The Tin Man episode of Stargate suggests an older technology. Basically the SG-1 find an underground complex with only one inhabitant. This fellow makes robotic copies of the SG-1 team and they go back to SG-C and are found out to be robots with the souls of the SG-1. They go back to the other planet and find their real selves and leave the robotic selves to help run the underground complex. The underground complex and the robots are the remains of a dying civilisation that remained immortal by making themselves mechanical bodies. The acting is the classic film trick of twins or doubles. Only really Jack but also Sam get to talk to their doubles.