Orthrus

Orthrus was a duplicate of K9 created by Drake.

Biography
Orthrus was created by Drake to frame K9 so he could dismantle him. It took "50,000 man hours" to create him. In his first task he appeared when June Turner was making a statement to protesters about Department Microchips. When they started throwing fruit Drake angrily ordered the CCPCs to arrest them, Orthrus suddenly appeared and opened fire on the Department's banners and Balloons he then shot Drake. Drake then issued a warrant for K9's arrest. When K9 said he had no memory of the attack Professor Gryffen put a device on K9's tail to see if he went "walkabout" during the next night. During that night Orthrus went into the mansion and severely damaged Mariah, A sentient Car owned by Gryffen and whom Darius Pike (Who Drake asked to join him) had a strong connection with. Darius was furious with K9 and Drake sent two CCPCs to arrest K9. Despite what he thought K9 done, Darius attacked a CCPC and ran with K9, Starkey and Jorjie. When they split up Darius was alone with K9 (actually Orthrus), he noticed him acting oddly and ran when he opened fire on him. He told Starkey and Jorjie what happened but they didn't believe him. When Orthrus came it armed its cannon at Jorjie, Starkey stepped in her way to protect her. When Orthrus prepared to fire he was fired at by the real K9. Orthrus tried to attack K9 but was disabled. When Drake came in and tried to arrest K9, June Turner told Drake that Project Orthrus was not approved by Department and his plot was foiled.(K9TV: Jaws of Orthrus)

It's unknown what happened to Orthrus afterwards but it's likely it was dismantled

Technology
Orthrus had all the basic capabilities of K9 such as Flying and a Photon Cannon. However since Orthrus was created using Department technology from 2050 and K9 was created in the 51st century with possible Time Lord modifications, it was inferior to the original.

Behind the scenes

 * Despite the fact K9 is voiced by John Leeson, Orthrus never spoke.
 * Orthrus is, in a way, the Valeyard of K9.
 * In Greek Mythology, Orthrus was a two-headed dog, brother to Cerberus.