#!/usr/bin/perl
use warnings;
use strict;
use feature qw(say);

my %hash;

push(@{$hash{Lemon}}, 'Juice');
push(@{$hash{Lemon}}, 'Cake');
push(@{$hash{Lemon}}, 'Juice');
push(@{$hash{Lemon}}, 'Cake');

my %uniq;
undef @uniq{@{$hash{Lemon}}};
say for keys %uniq;