meaning you would like to pay twice, to access lounges in both the North and South terminal, or were you planning on lounging in North and then heading to South to get through security again and go straight to your boarding gate?

(You cannot do what you propose. If, somehow, you managed to get airside at the North Terminal, you would need to seek assistance in order to get back landside again in order to board the train to get back to the South Terminal)