[davidpm]

In the "Wing" One-minute guide book on page 34 it says that for power-driven 50m or more the second white mast head can be an all-around so you don't need a separate stern light for inland.
At least that is how I interpret the graphic below.

International requires a separate stern light.

The end result is the same light configuration visible.

Do you know what page it is on in the USCG rules book, I could not find it?

Not sure why it matters as they look is pretty much the same except for the height of the stern light.