Twin kittens

This was 1975 and these were two siblings born at the house I shared
with a half-dozen other people. This was our backyard. What little
colour film I used back then was slide film, usually whatever cheap E6
film I could buy. (Kodachrome was very expensive for a poor student.)
I used a small WW2-era German viewfinder camera that I had bought for
five or ten dollars from a friend. His father brought it home with him
from the European war. My friend now had graduated to a Japanese slr.

I can remember the name of one of these kittens, Guinness, but not that of the other.