I've no experience of D-76, but in my experience with other products (and I'll probably be jumped on for saying this!) a minute here or there makes little difference in B/W film development. Variations of temperature, exposure, time taken to pour out developer and pour in stop bath all make it rather less precise than we may like to think, try as we might to make it otherwise. If you really want to develop the films together, I'd aim in the middle and neither should be very far out. Of course, it depends on the importance of the subject material - if it's your daughter's wedding or the flying saucer that landed in the back garden last night, then develop them separately......
Last edited by Steve Roberts; 10-26-2011 at 06:04 AM. Click to view previous post history.