Unicode was originally proposed as a universal character set to replace all existing character sets. For it to have any chance of acceptance it had to be possib

Unicode was originally proposed as a universal character set to replace all existing character sets. For it to have any chance of acceptance it had to be possible to convert from JIS/whatever into Unicode then back again without any loss of information. So if there were any daft duplicates in legacy character sets those had to be duplicated in Unicode. I don't know if that explains those three physical units, but that's what I'd guess happened.