Datalore

The Enterprise visits Omicron Theta, the abandoned colony where Data was discovered. In a hidden laboratory, the away team finds the parts of another android identical to Data, and brings them aboard. Reassembled, he calls himself Lore and claims to be the more perfect brother, built before Data by the colony's creator, Dr Noonien Soong. Lore explains that the colony was destroyed by a crystalline entity that feeds on life. In truth, Lore was in contact with it. He disables Data, takes his place and prepares to hand the Enterprise over to the entity. Wesley sees through the deception, but nobody believes him at first. Wesley and Dr Crusher reactivate Data, and together they find Lore in a cargo bay signalling the creature. Data fights his brother, and Wesley beams Lore into space. Without its ally, the entity departs.