my @allvalues;
for my $i ( 0 .. $#AoH ) {
   push ( @allvalues, $AoH[$i]{ page } );
}
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In general, building up an array by pushing in a loop can usually be done more elegantly with map/grep:

  my @allvalues = map $_->{page}, @AoH;
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However, if the only purpose for this array is to locate the duplicates for deletion, you don't really need this array or the duplicates array:

  # count occurrences of each value
  my %count;
  ++$count{$_->{page}} for @AoH;

  # keep only those copies that aren't duplicated
  @AoH = grep $count{$_->{page}} == 1, @AoH;
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That is:

  # replace @AoH with
  @AoH =
    # only
    grep
      # the hashrefs whose 'page' value appears exactly once
      $count{$_->{page}} == 1,
        # of the current @AoH
        @AoH;
[download]

Hugo