It's not a problem; this idea is genuinely counterintuitive when first encountered.

The reason it's counterintuitive is that you're accustomed to associating "ahartell" with a single sequence of connected observer-moments. Which makes sense: in the real world, it's always been like that. But in this hypothetical world there are two such sequences, unrelated to one another, and they are both "ahartell." That's completely unlike anything in your real experience, and the consequences of it are legitimately counterintuitive; if you want to understand them you have to be willing to set those intuitions aside.

One consequence is that you can both live and die simultaneously. That is, if there are two ahartells (call them A and 1) and A dies, then you die; it's a real death, just as real as any other death. If 1 survives, then you survive; it's a real survival, just as real as any other survival. The fact that both of these things happen at once is counterintuitive, because it doesn't ever come up in the real world, but it is a natural consequence of that hypothetical scenario.

Similarly, another consequence is that you can die twice. That is, if A and 1 both die, those are two independent deaths, each as real as any other death.

And another consequence is that you can live twice. That is, if A and 1 both survive, they are two independent lives; A is not aware of 1, 1 is not aware of A. A and 1 are different people, but they are both you.

Again, weird and counterintuitive, but a natural consequence of a weird and counterintuitive situation.