On Sat, 26 Dec 2015 02:21:46 -0800 (PST), bob haller
wrote:

te breaker that trips may have tripped a lot in its past, and be worn.
for lack of a better term.

i would first try replacing the breaker that trips

Yea, and the breaker that DOES NOT trip could be defective or even
internally seized up, which is dangerous. I'd also try replacing that
one too, and see if the new breaker trips in the same panel location.