So you're looking at the past to see the events which could have lead up to the present. There are two possible pasts, both of which, through the events involved in them, lead up to the present we have today. It doesn't really matter how similar or different they are.
TIMELINE
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Past 1| |Past 2
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V
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Present
Now as these pasts lead up too an identical present, there's obviously no observable evidence to say either one of them is more "true" than the other.
If both pasts lead to the exact same consequences, did either or both happen? If the actions I performed today have no observable differences tomorrow compared to the actions I didn't perform today, which ones did I do?