It's not 5x redundancy in that sense. There are times when the ship needs all five auxiliary engines. There are five smaller engines because it allows for more

It's not 5x redundancy in that sense. There are times when the ship needs all five auxiliary engines. There are five smaller engines because it allows for more efficient utilization. The main engine, which provides the propulsion, is a two-stroke engine connected directly to the propeller shaft. If the ship needs to reverse the engine is stopped, and started again going the other way. Consequently, there's no way to make use of some sort of fall back propulsion. Lastly, I doubt a 1000 HP engine is powerful enough to do anything useful. Especially because it would only be needed for emergency maneuvering.