For the epistemologically handicapped among you with this thought that only scientific experiments can prove anything ...
That all seems irrelevant to me.
Suppose they are correct, and on the quantum level two or many, even infinite realities exist.
WE are not on the quantum level, we are an expression of the Quantum when it becomes the Macro, and at those times the particles always go one way or another, they do not continue to exist in duality or multiplicity but fall into one place or another by mechanism not understood.
Even if superposition created two at the same time in the Macro, it would not be visible to us or affect us in any way we know of.
So no matter what they discover there, only its expression in the macro will affect us. If we someday learn those unknown mechanisms maybe they can be influenced, but not today.
So why concern myself with it?
Of course the problem is that any collapsing phase space probabillity still only leaves you with one final outcome that is observable and memorable and a whole host of unresolved realities that have not come to pass because they were not or could not be measured and then can not be proven to have been viable, simply existing only in potentia.
We are therefore left with the aim of preselecting a desirable outcome and bringing it about by observing and measuring, which is for the greater part what we do anyway.
We are of course then faced with the problem that on a greater scale there is not simply one observer, there are literally billions all exerting an influence and producing a cumulative result. The experiment can only present the possibility of a microcosmic and localised result dependent on the will of the eponymous "friend".
In finality we are left where we started with the idea that the world is what we make of it and the old maxim that "Creation is an act of sheer will”