Have a love /hate with tandem breakers. When one burnt up it would often burn the case on breaker above it and a few times when I turned that breaker off it would not reset ( never over a 20 amp tandem ). Would try not to use them on circuits that would draw loads over 10 amps or so. ( window air conditioners, kitchen counter top receptacles & laundry area ). Now with AFCI or GFCI required on just about every residential circuit they will be few in houses.