State A (original)
Snapshot 1 (from State A original, like a clone), you can run something against it and see how it works.
State A moves on to State B based on external influence
Snapshot 1, should be disregarded and make a new snapshot of State B. So we are back to a new version of a Snapshot 1
What would happen in your scenario is this: Snapshot 1, run external influence against it, make Snapshot 2, run a new external influence against it. Snapshot 3.
However State B doesn't necessarily represent Snapshot 2 because it might have been influenced differently. If it was exactly the same type of influence in the same order, then I can understand that the tracking would be similar and predictable, but it highly unlikely. Those small influences adds up a ton in the future.
edit: my point is, you can only predict a small amount of the future of what will happen, but sooner or later it will become clear that they will run separate paths eventually. Almost like parallel universes.