Based on your recommendation i wrote this:

use Win32::Unicode;
my $wdir = Win32::Unicode::Dir->new;
$wdir->open(@ARGV);
my ( undef, undef, $file ) = $wdir->fetch;
print join "\n", "length: " . length( $file ) . ", code points:", map 
+ord, split //, $file;
[download]

Which gives the below result, which is identical with the weirdly "upconverted" unicode above, and without further processing useless, as it doesn't map to anything but mojibake on any codepage known to me. (And ACP gives me 1252, sorry for speaking inaccurately about that.)

d:\>perl filename_check.pl RJ209072
length: 17, code points:
226
123
226
78
233
9524
196
113
233
9568
196
191
233
8976
233
189
50
[download]