When weighing out the advantages and disadvantages of twin engine versus single engine turbo-prop aircraft, most operators will think of safety first. Having the redundancy of a second engine means that in the case of an emergency where one engine quits and the aircraft has enough altitude, the second engine will provide the pilot with the ability to navigate to an emergency landing location. Aircraft with twin engines also generally have more backup components such as twin starter generators which provide additional safety in the event of failure.
There are also performance and operating cost differences between single engine and twin engine turbo-props. In general, twin engine aircraft allow for faster speeds, and faster pickup, while single engine aircraft have lower operating costs, due to maintenance and fueling for only one engine.
If you’re mindset is safety first for pilots and passengers, a twin engine aircraft makes sense for peace of mind alone.
>> See here why customers buy the Viking Twin Otter twin engine.