The other day, out of boredom, a friend and I were testing the new APIs out and watching the X-Rate-Limit data coming back. Using an OAuth will give you the 120. When we used the same client ID - without OAuth, from different IP addresses, I can tell you that he and I both had the same 30-uses, as we both counted down together from 30, not intertwining.
You could do what we did and test out the new API calls and watch the X-Rate-Limit data like we did and see what you see as well.