Basic Double Capture mechanisms are reviewed for collisions of highly charged ions with atomic target in the keV energy range. It is the main goal of this paper to clarify the relative role of the electron-nucleus and electron-electron interactions. First two independent electron models (IEM) are briefly described: the classical over barrier model and the quasi-molecular model. They account well for the population of configuration with two equivalent electrons. It is then shown that e⁻-e⁻ interaction is necessary to account for the population of doubly excited states with two highly non equivalent electrons. A special emphasis is given to a recent work on the stabilisation mechanisms responsible for true double electron capture.