One observation is that I don't think you need the %import hash. (In fact you aren't using it later in your script) You could append the items you find in the second file to the items you have already collected in the %import hash.

while (<IMPORT>) {
        my ( $machine, $user, undef, undef, undef, undef, $locale, und
+ef ) =
                split(/,/,$_);
        push(@{$scanned{$machine}}, $user, $locale);
}
close (IMPORT)
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Hope that helps.