#!/usr/bin/perl
use strict;
use warnings;
use autodie;

my %seen;

open my $FHIN, '<', $ARGV[0]                    or die $!;
open my $FHNEW, '>', "$ARGV[0].new.csv"  or die $!;
open my $FHDEL, '>', "$ARGV[0].deleted.csv"     or die $!;

foreach my $line (<$FHIN>){
    my ($key, $rest) = split/,/, $line, 2;
    $key =~ s/ [-&_+'] / /msx;
    $key =~ s/ ( [a-z] ) ( [A-Z] )/$1 $2/msx;

    ($seen{$key}++) ?
        print $FHDEL "DUP, $line"  :
        print $FHNEW "$key,$rest";
}

close $FHNEW, $FHDEL;