Ok, In Edit/Duplicate Array/Rectangular Array, for example I can setup 5 columns, 5 rows, stacks is grayed out with (8) in background, distance columns is 2, distance in rows is 2, dist in stacks is grayed out with 25 in background. Hit Ok and I will get 5 rows and 5 columns of my object with 8 duplicate stacks on top of each other. Hope this will help.