setup:
Having obtained the objective for double trouble I decided to experiment for doing dual descent.
I removed everyone but Jim and Panda to see my gold bonus and DPS at my current levels for those.
I then replaced Jim with someone/anyone else, or I then replaced Panda with Hermit or anyone else, and my DPS instantly went to exactly 0.
I knew it wasn't 0 but the monsters thought it was, so I moved to the next area forward or backwards and my DPS then was a real number and not zero.
that's the bug somehow on replacing one character with another you get 0.

then I looked so see what area I could coast on unattended for several configurations of 2 people. but that's a different story and not part of the bug.