Someone splits your body and soul instantly. You appear next to yourself, totally identical. Same mindset, memory, ego, everything.
If someone offers to kill one of the two copies and greatly reward (1 billion euros for example) the other self, what would you do? Will each of these selves be willing to sacrifice themselves so the other can get the reward? Since you are identical, you(one of the selves) still live with 1 billion like nothing happened, you won’t feel anything wrong except maybe some remorse for how the other self would feel?
After all, is there any difference between this self-split and the current multiplicity of people? For example, the experiment might be almost identical if you have another human being opposite of you instead of the self-split.