I think all you need to do is implement the code found below. What you need is instead of using the random numbers (like in my example), you would just give it the values for you bar graphs. You can then build an array where you append the values for the second color above the first color by using the add function. If you then go into the plot legend (left click and go into bar plots), you can change the presentation of the data on the graph. You will also have to change the common plots display in the legend as well (left-click and go into common plots). I hope this helps!
This is a very old forum post. Per the community rules, you should make a new post so you can hopefully get more traffic since more forum users will have a chance to see your questions.