Better would be to get an md5 digest of each file. Very easy with perl 5.8 and PerlIO::via::MD5,

use PerlIO::via::MD5;

my %digested;
for (glob '/path/to/*.csv') {
    open my $fh, '<:via(MD5)', $_ or warn $! and next;
    my $sum = <$fh>;
    exists $digested{$sum} and unlink($_), next;
    $digested{$sum} = $_;
}
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That takes care of deleting duplicates as you go. The file to survive among duplicates is the first one seen.