In toy model A we add an extra negative charge compared to toy model 0. The total energy of the system is shifted negatively compared to tm0 and the monopole shift is -2εC/2l. This could be because we need to take the interactions of the outer negative charges with the negative charge inside the dumbell into account. The added negative charge lowers the total inner charge, lowering the interaction with the outer electrons, which might then lead to a total positive contribution of the monopole shift.