Suppose A(+)B(-) type fused salt is present in an electrolytic cell (not electrochemical cell). Let n electrons be entering the cell per second. Since each A(+) requires one electron to discharge, so n electrons will discharge n A(+) per second. Similarly, n B(-) are also discharged per second because the number of electrons entering and leaving the cell must be same. Now, each A(+) has unit positive charge and hence n A(+) means ne(+) charge flowing towards cathode. Also, n B(-) means ne(-) charge flowing towards anode or we can say ne(+) charge towards cathode. Does that mean total 2ne(+) charge is flowing towards cathode per second ? However, from above only ne(+) charge is entering the cell.