Portable Electric Generator 2-Pole Circuit Breaker 16.3A Trip, BSB1-30

This breaker is used, but in a generator that ran for only less than an hour.  It was pulled from a DuroMax XP4850EH and replaced by a higher 20A trip current breaker.  At 240VAC output, this breaker should support up to 3900W which is much less than the generator rating of 4850W.  I think it was factory installed by mistake.