The letters on the buttons on the controller at the end are a bit different.....I like.

It is a generic sound which was used in many games, not only Warcraft II. I also found myself often hearing a sound in some movie or advertisement which I know from some game, and wondering if it's from some big source of a freely available sound pool.
Grabbing an already existing, freely available sound file is cheaper and takes less effort, than making an own one ;)

http://memebase.com/2011/01/30/memes-professor-layton/

I had to google what this Professor Layton is, but the pun is hilarious.

After I thought about it for a while, I realized that was the much more likely solution. But the idea of Duke doing a really subtle rip on Blizzard was alot of fun to think about.

A couple of years ago I saw this preorder ad for Command and Conquer 3 and was extremely surprised to hear in the ad this same bit of public domain music that a friend and I ourselves had used in a film we had made. Weird stuff that public domain.