Yes, Mustang is right.
I was considering to get twins for my Rib as I often fish alone and 12 miles off shore, but as I am in the market for a GW Canyon I will need twins, so that consideration is cleared.
Seems not really an issue, but we don't have SeaTow or similar help, if my engine dies I have to call Costa Guard.
Twins can be useful to save lives, but not always as engine failure will depend of the reason for failure.
Limping home with one engine will often work but serious troubles with fuel system, electrical system will not allow that and if the reason is a spun propeller the second one may fail on the way home too if they have same age.
Some insist to be able to swap a defective propeller off-shore, I did it in the marina and it was no fun and I have to admit that I dropped the propeller nut.... Having a spare propeller aboard should include mask, snorkel and good, long fins, bigger outboard propeller are heavy beasts, particularly without fins.
A kicker with a completely separate fuel tank and hoses is a good backup system, however the choice of the right kicker and it's installation is very important. Often a kicker is useful for slow trolling too, but on a heavy boat the power will be insufficient to push the boat under nasty conditions, but e enough powerful kicker will be too fast for slow trolling.
And often nasty conditions are the underlaying reason for engine failure
Safety concerns should include not only two outboards, but also and very important to have the boat in best conditions.
Replace propellers every xx years, check and replace batteries every xx years, check fuel filters for debris and water, fuel lines for any kind of damage and if in doubt replace them.
Well then also thru-hulls, their hoses, bilge pumps, etc, but that's not propulsion related but still is one of the biggest hazards and sinking is ways worst than drifting without propulsion.
A good and in working order toolbox and the knowledge to use it is a big security plus as some/a lot of dead engine problems could be fixed rather easily if tools, parts and knowledge is aboard.
Chris