use Data::Dumper;
use strict;

my $AoH = [ { page => 'spring',
				 chap => 'spring'},
            { page => 'winter',
				 chap => 'winter'},
            { page => 'fall',
				 chap => 'fall'},
            { page => 'summer',
				 chap => 'summer'},
            { page => 'spring',
				 chap => 'spring'}
          ];

my %uniq = map { $_->{page} => ; $_->{chap} => 1 } @$AoH;
@$AoH = map { { page => $_ };{ chap=>$_ } } keys %uniq;

print Dumper ($AoH);

##</code><code>##

$VAR1 = [
          {
            'chap' => 'summer'
          },
          {
            'chap' => 'winter'
          },
          {
            'chap' => 'fall'
          },
          {
            'chap' => 'spring'
          }
        ];