Hmm... Well, if we're all from different worlds, but even world travelers haven't been to most of these worlds, then it's possible it's because we're not all from the same reality. So, if that's the case, maybe there's another reality where some guy who looks like you knows about the Unversed but not Heartless, and coincidentally enough knows about Keyblades as well.
And because there's some lack of originality going on, they probably mimicked every other guy you know too just to try messing with you.
[Filter] They'd be all sparkly and rainbowy, people will stare ;3;
Hmm... Well, if we're all from different worlds, but even world travelers haven't been to most of these worlds, then it's possible it's because we're not all from the same reality. So, if that's the case, maybe there's another reality where some guy who looks like you knows about the Unversed but not Heartless, and coincidentally enough knows about Keyblades as well.
And because there's some lack of originality going on, they probably mimicked every other guy you know too just to try messing with you.