Preciso contar as duplicatas, elas precisam ser 100% idênticas para aumentar minha contagem, mas não posso usar nada do Ruby 1.8.5, esse código vai rodar dentro de um plugin no google sketchup

API do Google Sketchup Ruby

puts VERSION
1.8.5

puts RUBY_PLATFORM
i686-darwin8.10.1

product = 'Glass'
x = width
y = length
z = density

product_list = [
                { "product" => 1, "x" => 200, "y" => 100, "z" => 18},
                { "product" => 1, "x" => 200, "y" => 100, "z" => 18},
                { "product" => 1, "x" => 300, "y" => 100, "z" => 18},
                { "product" => 2, "x" => 300, "y" => 100, "z" => 18},
                { "product" => 2, "x" => 100, "y" => 100, "z" => 18},
                { "product" => 2, "x" => 100, "y" => 100, "z" => 18},
                { "product" => 3, "x" => 100, "y" => 100, "z" => 18}
               ];

product_list_result = product_list.count_duplicate();

product_list_result = [
     { "product" => 1, "x" => 200, "y" => 100, "z" => 18, "count" = 2},
     { "product" => 1, "x" => 300, "y" => 100, "z" => 18, "count" = 1},
     { "product" => 2, "x" => 300, "y" => 100, "z" => 18, "count" = 1},
     { "product" => 2, "x" => 100, "y" => 100, "z" => 18, "count" = 2},
     { "product" => 3, "x" => 100, "y" => 100, "z" => 18, "count" = 1}
                      ];