Although seen here in its own right, this negative has also been printed on the same piece of paper as a different negative.
The practice of copying two negatives on the same piece of paper at the same time would have doubled the rate at which photographic prints could be produced. Not only did this make the best use of supplies, such as paper and chemicals, it would also have made the best use of time and available sunlight.
See also Schaaf numbers 442, 332 and 333.