I've seen discussions about the minimum amount of stock D76 for one roll of 135 or one roll of 120 hashed over many times here and elsewhere. It's still unclear to me.
The Kodak datasheet says
One way of interpreting this is that the minimum amount of stock to be used for a single roll is ~250ml and so 1+1 requires a total volume of ~500ml including the diluent.
Originally Posted by Kodak
In other places I've seen different interpretations, and I've seen other folk say 100ml stock is enough for a roll.