Why is changing all data?

Please help! This is driving me crazy. I don´t understand when populating TodosLosTurnos3x8Encontrados through an auxiliar variable called Turno3x8Aux in line 

114 Turno3x8Aux.CtasEn3x8.add((3*(i-1)+k));

when k= 85 is the problem, it is supposed to add {1,2,3,4,5,6} only to the current TodosLosTurnos3x8Encontrados, however it changes all previous tuples (with values {1,2,3}) as soon as the line 114 is executed.!!


                    for (i=1;i<=NumSect3x8;i++){
                        for (k=1;k<=3;k++){
                    if (NumSect3x8>0){


Source: Why is changing all data?