Because there ought to be a difference between the two scenarios, unless they are identical.
Science doesn't deal in oughts. Which is which?
By the way, speaking of oughts, what are your thoughts from the perspective of philosophy, of the two slit experiment?
Reasoning from first principles, should physical objects be capable of being in more than one place at the same time? Should physical objects be able to take multiple, simultaneous paths from one point to another? should physical objects be able to move from one place to another without traversing the intervening space?