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

my %data;
while (<>) { # reads 2 files from @ARGV - filenames are on the command line
	my ($id, $val) = split;
	push @{ $data{$id} }, $val;
}

for my $id (sort keys %data) {
	print join("\t", $id, @{ $data{$id} }), "\n";	
}