What you see in the media concerning "parallel universes" is just a dream.what would be defined as evidence of a parralell universe and what are the expectations of it to be excepted as the differences in what people expect to be defined as evidence is so different as everyone thinks differently so what they would define as evidence would all vary and be different
What's actually going on in the scientific world is the search for extra dimensions. From that, some people extrapolate whole universes in these extra dimensions.
From what I've read of it, it appears that if there were entire universes in these extra dimensions (if those even exist) then light would not propagate in those other universes - so they wouldn't be places where doppelgangers of us were going around living lives similar to ours.
As far as what would constitute evidence for extra dimensions, this article - though somewhat outdated - lays out several scenarios they've examined, or will examine, at CERN.