Brothers in Arms by Lois McMaster Bujold (American, 1989)

Summary:
Admiral Miles Naismith leads his mercenary troops, the Dendarii, to Earth. Once in that alien planet, he is forced to reverse to his true persona, Miles Vorkosigan, son of one of the most prominent military men in his home planet Barrayar. While on Earth, Miles is to remain hidden inside the Barrayaran embassy in order to protect his other identity from the politicians gathered in London. 
 Since Miles is neither able to remain idle nor follow orders, he finds himself some spare time from his duties and investigates the disappearance of his superior, Duv Galeni. Aided by his love interest and personal body guard, Elli Quinn, Miles manages to contact Galeni’s kidnappers. The two parties agree to meet in an abandoned house in order to negotiate Galeni’s release. Once at the meeting spot, the kidnappers create a diversion which forces Elli and Miles to separate. It turns out that the meeting was a trap created for the sole purpose of replacing Miles with a clone. Unaware of the plot or that the real Miles has been captured, Elli leaves for the Barrayaran embassy with the clone. 
 When Miles wakes up he finds he is being imprisoned in the same cell as Galeni. Their kidnapper is, actually, Galeni’s father, Ser Galen, leader of a group of Komarran rebels, who are all bent on re-initiating a war with Barrayar: their plan is to infiltrate in the Barrayaran government and have the clone, passing as Miles, assassinate the Emperor, which would lead to a civil war that will finally make Barrayar an easy target. Elli is able to free Galeni and Miles after a few days. His scheme being discovered, Galen kidnaps Ivan Vorpatril, Miles’s cousin, and arranges another meeting with the latter. As Galen is ready to kill Miles and frame his clone for the murder, Miles convinces his clone to seek his freedom; Mark, as Miles names his clone, shoots Galen dead, helps Miles to rescue Ivan, and with their help travels to the space station in which he was created with the purpose of freeing his fellow clones and ending the cloning market once and for all.

Another summary:
Miles is a barrayan mercenary who is known as "Admiral Naismith" and also as "Lord Vorkosigan". He does this with the intention of making the mercenaries, who are enemies, and the cetagandos think that he is two different people. Only him and his right hand, Elli Quinn, know that he is only one individual. After some unfortunate events because of the confrontations with the cetagandos Miles fleet runs out of funds to keep operations running. After this, they have to carry out a mission in which Miles finds out there is a clone on the side of his opponent. After being kidnapped and interrogated, he tries to convince his clone to help each other so that they solve that situation, but he fails. Some days after the kidnapping, he is sent to be assasinated but miracolously he is rescued by his team. While this happens, the clone pretends to be Miles in his fleet in order to create a disaster in the barrayan planet.
 After Miles is liberated, he ends up forcing his clone to cancell his plans and run away from the authorities. Miles gets obsessed with his clone and tries to treat him like a brother, he wants him to remain alive. This ends up in a suicidal mission after negotiating with his clone to get him out of the planet alive along with his tripulation and before being found by cetagandos.

Another summary:
The story is about lieutenant Miles Vorkosigan who has a double identity as admiral Miles Naismith, a mercenary. After a mission in which his ships are damaged, Miles is forced to land on old Earth. 
 Now on Earth he has to report to the Barrayaran Embassy in London to collect his payment of the last mission. In there, he has to report to the Captain Duv Galeni and assume his true identity. In that same place he meets with his cousin Ivan Vorpatril. After a few days having stayed at the Embassy, Galeni mysteriously dissapears. 
 Miles, intrigued by this event, starts to investigate what is going on,then he discovers that there is a plot in order to bring down the Barrayaran empire organized by the Komarran and led by Ser Galen, Galeni's father, plus there is also a clone of Miles, Miles is captured and finds out that Galeni was also captured. The clone supplants Miles and just when Miles and Galeni are to be executed, they are rescued. 
 Galen then captures Ivan and forces Miles to face him and his clone. Once they meet Galen orders the clone to kill Miles, instead he kills Galen and runs away. Things get worse when the Cetagandan and Barrayaran assasins start looking for Naismith. Miles, along with the clone, proves that Naismith and Vorkosigan are two different people and are able to escape. Miles recognizes the clon as his brother and names him Mark, gives him money and the opportunity to go to Barrayaran and claim his place or run away.

World view: Describes in a variety of aspects and with some consistency an imaginary state or society which is regarded as better, in some respects at least, than the one in which its author lives.
Future projections: It’s a negative emotional reaction against technological (transcendental, evolutive) or social progress. As such, It shows the horrible consequences of utopia or at least portrays skepticism or disappointment in regard to scientific or technological miracles.
Ideology: Portrays the enforcement of justice in a positive manner and has faith in human capacity to build a better future.
Characters, plot and writing style: Black humor and satire are employed to expose, criticize or shame individuals or the society itself into improvement.
Classification: Dystopia