Over, claims of visiting a parallel universe can range from 'everything is the same except [this big thing] never happened, so [this major difference] .' to 'People have pink hair and anime eyes, and telekinesis is real!'
One of those is a more plausible possibility. But neither is ever going to be verifiable.
When people venture on any non-physical travel (by whichever tradition, and whichever name), the perceived journey is always unverifiable personal gnosis. It is all interpreted by the beliefs of the person who experienced the travels, filtered through their own mind.
None of it can be proven or disproven. Therefore, none of it can lie in the realm of fact, but only of faith or belief. It does not necessarily invalidate someone's experience. Additionally, just because more than one person may experience similarities is not a confirmation; it is simply a similar experience. This is sort of where a shared gnosis comes into play, in such examples as people having encounters with the same deity.
Even so, none of it can be quantified, or verified external of these individuals' own internal experiences. None of it can ever 'really' exist. People may believe they do, but that proves or disproves nothing.