I am really excited about this "new" explanation of what a generation is.
My great-grandfather was born in the early 1860's. His son, my grandfather was of the same generation being born before GG died. My father was of the same generation as his father, who was of the same generation as my great-grandfather. Still with me? Now I am of the same generation that my father is because we are both still alive. Now seeing that my father, and his father are of the same overlapping generation as my great-grandfather, and I am of the same generation as BOTH of them, that means I am of the same multiple overlapping generation as my great-grandfather. And we were only born one hundred years apart.
So, i know that isn't the exact way Splane 'splaned things, but it makes the same amount of sense.