JoinCSV

#!/usr/bin/perl
use strict;
use warnings;
use feature qw(say);
open my $csv1, $ARGV[0] or die;
open my $csv2, $ARGV[1] or die;
my $ret = {};
while (<$csv1>) {
  chomp;
  my @d = split /\s*,\s*/;
  $ret->{$d[0]} = [$d[1]];
}
while (<$csv2>) {
  chomp;
  my @d = split /\s*,\s*/;
  if ($ret->{$d[0]}) {
    push $ret->{$d[0]}, $d[1];
  } else {
    $ret->{$d[0]} = [$d[1]];
  }
}
close $csv1;
close $csv2;
foreach my $r (sort keys %$ret) {
  next unless @{$ret->{$r}} == 2;
  say "$r," . join ',', @{$ret->{$r}};
}