I just happened to look at the documentation on this which reads:
One column typically contains the unique identifier for a specific product, such as the ID column. A unique column may be selected from all available cart columns, but typically the ID column is used by default. 
That kind of goes against what we have discussed. It is the reason I appended time() to the end of my ID to make it unique because my product is somewhat complex as to the number of factors that make it a unique cart item.
You might want to update that in the docs.
Steven
