Are you asking if you can stack discounts on the external HDD that was "accidentally" thrown in?I did pick up the free printer and they accidentally threw in an external USB 250GB HDD by accident so it all evens out.
Out of curiousity, my parents have the corporate discount and I have a student one. Do they by any chance stack?
Do you realize people can lose their jobs over "accidents" like this? Or that, depending on the circumstances, something like that could possibly be construed as as theft on your part?
You can obviously do what you will, but if your screen name is accurate my advice would be to learn to listen to the little voice that tells you something isn't right as opposed to rationalizing it away.