Always have a back up. A back up firearm, a back up plan, and back up's for your back ups.
Yes, it's possible to dupe up too much. 2-3 layers seems about right and allows for a good mix of affordability and paranoia. Your house starts looking "hoarder-ish" and you've probably gone too far.
I thing I learned in the military; if you have a Plan A you’d better have a Plan B.