Full binary evolution HR diagram of the binary system considered in the example. Primary and secondary stars are born in the ZAMS (bottom right). Case AB (B) stable MT phase is indicated in light-blue (green). Afterwards, the primary moves to the left and collapses to form a first BH (black star). The secondary expands and a case AB stable MT phase occurs (salmon colour) until an unstable CE phase is triggered (grey circle). The detach of the secondary occurs at the blue (orange) circle for α_CE = 2.0 (α_CE = 1.0). A second BH is formed at the top left corner (coloured stars).