#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
use List::Util qw/uniq/;

my $file = 'file.txt';

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

my %hash;

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

foreach my $key( keys %hash ){
    my @array = @{$hash{$key}};
    my @uniq_elems = uniq @array;
    $hash{$key} = \@uniq_elems;
}

print Dumper(\%hash);

exit;