#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;

my $file = 'file.txt';

open( FILE, '<', $file ) or die $!;

my %hash;

while ( <FILE> ) {
    chomp;
    my $lines = $_;
    my $key = (split(/ /, $lines))[0];
    my $value = (split(/ /, $lines))[1];
    push @{ $hash{$key} }, $value;
}

print Dumper(\%hash);

exit;