See William Riker and Thomas Riker from Star Trek. http://memory-alpha.wikia.com/wiki/Thomas_Riker http://memory-alpha.wikia.com/wiki/Thomas_Riker William Tho

See William Riker and Thomas Riker from Star Trek. http://memory-alpha.wikia.com/wiki/Thomas_Riker http://memory-alpha.wikia.com/wiki/Thomas_Riker William Thomas "Tom" Riker was a result of a transporter accident in 2361 that created two William Thomas Rikers, genetically indistinguishable from each other, with personality and memories identical up to the point of the duplication. One of the duplicates continued to be known as William Riker. The other chose to use his middle name and be known as Thomas Riker. Thomas and William clashed almost immediately due to the resentment each felt towards the other. The eight years of living different lives made them entirely different men – William evolved into a cautious and duty-driven officer while Thomas remained impulsive and reckless. As a result of conflicts with William – who was by that time a superior officer (a commander) – Lieutenant Riker decided to leave the Enterprise. He chose to use his middle name, Thomas, to distinguish himself from his counterpart. Captain Jean-Luc Picard managed to get Thomas a posting on the USS Gandhi where he could continue his Starfleet career. Upon Thomas' departure, William seemed to have accepted Thomas' existence and gave him his trombone as a parting gift. (TNG: "Second Chances")