I have two comments on this thread...

The examples provided (I & II) do not necessarily show a correct pattern of either.  In the first example, the assumption can be made that the description is unique and thus requires a unique example.

The second is merely a reverse of the first, as a unique example requires a unique description.

Where the second pattern example fails is when you can have multiple examples of the same concept, thus requiring basically a single description.

For example here are two examples of adding to an integer variable in C#...

Both examples would only need a single description, which describes that there are several ways to increment an integer variable in C#; the first using plus(+) operator, the second using the plus-plus(++) operator.