$ perl -wE 'my ($x, $y) = "AB" =~ /(.)(.)/; say "$x $y"'
A B

##</code><code>##

$ perl -wE 'my ($x, $y) = "AB" =~ /(.)(.)./; say "$x $y"'
Use of uninitialized value $x in concatenation (.) or string at -e line 1.
Use of uninitialized value $y in concatenation (.) or string at -e line 1.
 

##</code><code>##

#!/usr/bin/env perl -l

use strict;
use warnings;

use Text::CSV;
use Inline::Files;

my %data;

my $csv = Text::CSV::->new;

while (my $row = $csv->getline(\*FILE2)) {
    $data{$row->[0]} = [ @$row[1..$#$row] ];
}

while (my $row = $csv->getline(\*FILE1)) {
    next unless exists $data{$row->[0]};
    push @{$data{$row->[0]}}, $row->[1];
} 

$csv->print(\*STDOUT, [$_, @{$data{$_}}]) for sort keys %data;

__FILE1__
an_en11,200.00,{0 133},{ }
br_gh13,140.09,{0 59},{ }
ce_oy74,300.05,{0 230},{int_43}
dt_pp50,200.11,{0 122},{ }
er_tk02,305.47,{0 220},{ }
ef_yb41,200.05,{0 233},{ }
__FILE2__
dt_pp50,0,0,2,0.000,0.000,0,0.000
er_tk02,0,2,3,0.002,0.004,0,0.001
ef_yb41,0,1,5,0.000,0.000,0,0.000

##</code><code>##

dt_pp50,0,0,2,0.000,0.000,0,0.000,200.11
ef_yb41,0,1,5,0.000,0.000,0,0.000,200.05
er_tk02,0,2,3,0.002,0.004,0,0.001,305.47