Doppelgänger (Original Timeline)

Within the Tomb Raider series there have been two doppelgangers of Lara Croft (featured in Tomb Raider/Tomb Raider: Anniversary, and Tomb Raider: Underworld).

First encounters
Up-to-date there's two doppelgangers of Lara, these all had their very own first encounters throughout the course of the game series.

The first doppelganger
The first doppelganger to be encountered was in Tomb Raider and Tomb Raider: Anniversary, found in 'The Great Pyramid.' Its appearance was skinless with no hair, gaining it the nickname 'Bacon Lara.' The creature seemed to have very limited intelligence, only able to mimic Lara's every movement. While it did not attack directly, shooting it caused damage to Lara herself. Lara was eventually able to trick it into jumping into a pit of molten lava, destroying it. It is hypothesized that this doppelganger was just an Atlantean creature copying Lara's every move because it did not have a motive. However, its appearance in Tomb Raider: Anniversary, as well as an entry in Lara's journal in Tomb Raider: Underworld contradict this.

The second doppelganger
The second doppelganger appeared in Tomb Raider: Underworld. It was created by Natla and Amanda Evert, and unlike the first version is easily able to pass for human. Mentally, the doppelganger appears to be very much like Lara herself, sharing a similar personality and intellect; the main difference is her compulsion to follow the orders of anyone who knows the proper command word. In physical terms, the doppelganger is far superior to Lara, possessing far greater speed, strength, and agility. While nearly identical to the real Lara, the doppelganger does have some visible differences, the most notable of which are her glowing gold eyes. Her overall appearance is closer to that of Lara's traditional Tomb Raider character model, with red hair, brown lips, and a hairstyle similar to that seen in Tomb Raider 2.

During the course of Tomb Raider: Underworld, the doppelganger is ordered to place a bomb in Croft Manor, which ultimately destroys the mansion. Zip, unable to tell the difference, later opens fire on the real Lara, believing that the bomb was her doing. Lara returns to the burning main hall to check the security cameras, where she encounters the doppelganger face to face. She attempts to manipulate its behavior as she did the first doppelganger, but it only plays along for a few moments before murdering Alister and fleeing the manor. They later meet again in Helheim, but their encounter is cut short by Amanda.

In the DLC Lara's Shadow, the doppelganger--still under Natla's control--retrieves Natla from Helheim and returns her to Atlantis in order to heal her. Once stabilized, Natla orders the doppelganger to kill Lara, then herself. In the meantime however, Lara had learned the command necessary to control her, and uses it to stop the doppelganger in her tracks when she arrives. After a brief conversation, in which Lara questions the doppelganger regarding her nature, Lara sets her free of Natla's control, and in return tells her to "make sure Natla suffers." All too happy to cooperate with Lara, the doppelganger returns to her birthplace, destroys Natla's regeneration chamber, and watches with a smile as Natla herself drowns in a pool of eitr.

Fate of the doppelgangers
The fate of the doppelganger and its whereabouts afterward are unknown.

It is most likely that the first doppelganger might be dead after the explosion that occured at The Great Pyramid.

Trivia

 * In Tomb Raider, the doppelganger looked nothing like Lara; it was extremely thin, had large alien eyes and a human looking flat chest making it seem like it was male.
 * In Tomb Raider Anniversary and Underworld , the doppelgangers looked more human, and looked more like Lara Croft.
 * One of the doppelgangers appears as a costume for Lara in Tomb Raider Anniversary.