Shoot two short rolls with some test shots of a target you make, including a step wedge, gray card, colour chart, and some colourful items that you can set aside. Use very repeatable lighting, such as high noon outdoors, or flash with fresh batteries, waiting double the recycle time between flashes, or incandescent light, either one at an accurately measured distance. Include a note in the shot saying whether it is roll #1 or #2.
Originally Posted by streetshot
Develop one roll at the beginning of a batch. Run your 90 or so rolls through and develop the second roll as the last one.
Compare, perhaps by printing the two (35mm?) strips side by side in a 6x7 negative carrier onto the same piece of paper.