Dalek duplicate

The Dalek Duplicates were genetically engineered soldiers created by the Daleks. They were conceived as copies of individuals killed by the Daleks, to be used in undercover work. Despite this, the duplicates retained some memories, leading them to fight their programming. On Bliss, the replicants gained a reputation. (AUDIO: Enemy of the Daleks) The Supreme Dalek planned to use a duplicate of the Fifth Doctor to assassinate the High Council of Gallifrey, but he escaped before the duplicate was completed. Davros converted some of the duplicates to his own cause and they were all killed off in the crossfire between the renegade and imperial Daleks. The Supreme Dalek vowed to create more duplicates and invade Earth. (TV: Resurrection of the Daleks)

Upon being brought aboard the Combined Galactic Resistance command ship, Aristotle, the Twelfth Doctor and Clara Oswald were treated with suspicion by Colonel Morgan Blue, under the precaution they could be duplicates. (TV: Into the Dalek)

Biology
Duplicates were incredibly strong and were able to perfectly mimic voices. Among some issues with replicants were their cold skin, (AUDIO: The Genocide Machine) and eye colour, which the Daleks could never get right. (AUDIO: Daleks Among Us)