You have used the pattern /./ on which to split the string. '.' is a regular expression metacharacter which matches any single character (except the newline in multi-line matching) so your split isn't doing what you want. You should have escaped the metacharacter like this

my ($filename, $code_number) = split(/\./, $_, 2);
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so that you are splitting on a literal full-stop.

Also, your

    next if ( $_ eq '..' );
    next if ( $_ eq '.' );
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can be more neatly achieved by

    next if /^\.\.?$/;
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Cheers,

JohnGG