S1, E6: On Planet P3X562 the SG-1 team discovers a valley full of broken crystals. Alone O'Neill finds a whole crystal with blue light emanating from it. Upon touching it he is struck down and a duplicate O'Neill appears. The double returns home through the Stargate with the unsuspecting team. Once back the double seeks out O'Neill's estranged wife Sara and tries to find the couple's son Charlie who was killed years earlier. Meanwhile a revived O'Neill returns through the gate only to realize he's been replicated. Carter and Jackson have discovered that the crystals contain energy beings that can read minds mimic people and communicate. The beings tell of their tragic encounter with the Goa'ulds and explain that they cannot survive in the Earth's intense electromagnetic field which means that the O'Neill double is now highly unstable putting Sara and others in great danger. The real O'Neill and the SG-1 team find Sara and the double in a hospital emergency room. The double explains that he never meant to hurt O'Neill. He was trying to heal him when he realized that the greatest pain O'Neill had was not physical but emotional; grief from the loss of his son. In a final gesture the double does just that taking the form of Charlie and giving Sara and Jack something they never had: a chance to say good-bye to their son.