Then I assume you've never input a hotfix or a patch, because Microsoft does
that all the time with their fixes. The problem is, they done't always know
every place it might exist and people install software with older versions
that don't check the system for more recent versions, and so they get out of
sync.
They sell programs that actively search for such duplicates to preserve the
most recent version and remove or replace the obsolete "duplicates." Often
the system gets cluttered with a host of versions.
I've yet to see a DLL that isn't fully backwards compatable - but then
again, I do learn something new every day. IMHO, if the source of the file
is valid (e.g., Microsoft and not Joe Schmoe from the South Pacific), the
most recent version is the only one that should be on your system at any one
time. The obsolete duplicates can only cause problems and I do not believe
the more recent releases will cause any backwards comapatability issues
whatsoever.
....But I'm always willing to learn. Can you point out an article that
specifically recommends keeping multiple versions of the same DLL
(especially when both were from the same vendor - Microsoft) because the
newer ones cause problems with older software?