Indeed. I'm sure I've lost irreplacable data in the past, but I can't remember what it was, and suspect that if I still had it, I'd look at it quizically and ask myself 'what was that all about, then?'
I think there's an implication of non-interchangeability. Your six-year-old's first painting is irreplaceable because some other kid's painting won't do; someone else's six-year-old's first painting is not irreplaceable because one such painting is likely to be of as much interest to you as any other, even though when your house burns down you won't be able to get exactly the same painting back.
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