On Altair, Harlan duplicated SG-1 by creating "synthetic others," exact replica robot bodies which contained a copy of the consciousness of each team member. The duplicate team demanded that they be returned to their human bodies, and did not realize that they were copies until they came face to face with their original counterparts.
The synthetic duplicates were "better," stronger, smarter, than the originals, but their synthetic bodies had limited reserve power. They relied upon a continuous stream of energy from an emitter in the ancient underground power facility and therefore were unable to survive for more than a few hours off-world. They remained behind on Altair, but they did not bury the gate as promised. The duplicate Carter created a portable reserve power pack worn in the chest, which would last 48 hours before needing to be recharged, as well as an internal radio for communication. Not content to remain on Altair, the team began going on off-world missions, until they were captured on Juna and their original counterparts were sent on a rescue mission. The duplicate team was destroyed when they cooperated with SG-1 in the joint battle to defeat Cronus and free Juna.
In an attempt to create a similar technology, SGC scientists hoped to modify an android body recovered from PX3-989 and to incorporate the experiences of every SG team member since the inception of the program into a viable artificial intelligence. Their project hasn't received funding, however, and has not progressed much beyond a concise 380-page report.
Cross Reference: Altair, Clones, Comtrya, Cronus, Darian, Harlan, Hira, Juna, Sindar
Episode Reference: Tin Man, Double Jeopardy, Avalon