What shape metal object has two of the same color?
return objects ;return #1 that  are metal ;return colors of #2 ;return number of  #2 for each #3 ;return #3 where #4 is  two ;return #2 where #3 is  #5 ;return the  shapes of #6
['select', 'filter', 'project', 'group', 'comparative', 'comparative', 'project']