Tin Man

11,000 years ago, the inhabitants of the planet On Altair (P3X-989) were forced underground by deadly radiation, and eventually transferred their minds into exact android duplicates to survive. By the time SG-1 visits their planet, there is only one remaining individual, Harlan, who creates android replicas of the Earth team to aid him. When this is discovered, the androids must accept that they will stay off-world, and the real SG-1 returns home.