This can also be accomplished using the Data::Table module. This code:

#!/usr/bin/env perl

use strict;
use warnings;

use Data::Table;

my $t1 = Data::Table::fromCSV("d1.dat", 1, undef, { delimiter => " " }
+);
my $t2 = Data::Table::fromCSV("d2.dat", 1, undef, { delimiter => " " }
+);

my $t3 = $t1->join($t2, Data::Table::INNER_JOIN, [ 'id' ], ['id']);
$t3->sort('id', 1, 0);

print $t3->tsv;

exit;
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gives this output:

id  x1  x2  word
A   12  45  hello
A   10  12  hello
A   15  74  hello
B   23  15  goodbye
C   11  41  blue
C   18  12  blue
D   19  10  happy
D   11  12  happy
E   14  5   black
E   34  31  black
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