The correct answer to this open question is the following.
It is true that East Germany went to great lengths to build the Berlin Wall. I think it contained so many layers because the wall was built to avoid any kind of trespassing from one side to the other. Furthermore, it was a symbol of power, control, and dominion established by General Joseph Stalin, the leader of the Soviet Union during the so-called Cold War years.
I think that for the Soviets it was so important to separate the two groups of people to clearly show the world that the Soviet Union had its own controlled territories in Eastern Europe and no western European country, neither the United States, could mess with the USSR.
The Cold War years was a time in which the United States and teh Soviet Union competed in the arms race, the space race, and in spreading/contain COmmunism in the world.