This is out of curiosity. I just read another post about needing more space than a large trunk bag and did not want to hijack the thread.
I can fit everything in my trunk bag (homemade). I bring a soft lunch box, my scrubs rolled up, and various small accessories (lights, rain cover, extra warm accessories). I can pack shoes, but usually leave then at work. Lock get left at work too.
Just what are people brining that requires two panniers?