use List::Util qw(reduce);

my $array = [[apple, a1], [apple, a2], [apple, a3]]; 
my $result = [];
unshift(@$array, []);
push @$result, reduce { 
	push(@$a, $b->[0]) unless exists $a->[0];
	push(@$a, $b->[1]); 
	$a;
} @$array;