All right, it's done.

Yes. So let's say you have view controllers 1-5 where the left stack is (1,2,3,4) and the right is (5). The first method would allow you to, for example, pop to 1 being the displayed on the left and simultaneously slide in a new one (6) on the right leaving the state as the left stack being (1) and the right being (6).

Similarly, the second method would allow you to pop to 1 and push 6 and 7 so that the final state is (1,6) on the left stack and (7) on the right.