SGC is stunned when a cocky teen knave, stopped by security, claims to be the only Jack O'Neil, who is on leave but can't be found home, using is key card and knowing more than anyone else could. Daniel and Sam get convinced it's their colonel, but amnesiac and referring to an alien abduction of an Asgard type, actually fitting many civilian reports with a specific detail. Medical tests from military staff and Jacob's Tok'ra team show his body is decaying, due to a flaw in DNA manipulation, the teen proves genuinely knavish while competent as space pilots instructor. They call upon Tor, who concludes it's forbidden Asgard cloning, and set a trap for perpetrator Loki, recuperating adult Jack, while determining the duplicate's fate seems the moral nightmare.
—KGF Vissers