Your first reading of 8.2 will have been raised because of the chocolate, making it difficult to gain any useful information from the 2nd test.
To really understand how your meal of ham egg and chips affected your blood sugar, you need to know what your levels are immediately before(without chocolate)and at 2hrs . The difference in the 2 results shows how that meal affected you.
Now if you had tested just before you had the chocolate and again before you had the ham, egg and chips, you would have learned what the chocolate does to your blood sugar in 30min.
Like any test you need to have a clear Idea of what you are testing, for the results to be useful.