I hear ya, I too have always had a backup pump because I'm paranoid and believe in being ready. I still have it twelve years later. I've changed my main pump so many times I now have a closet of backup pumps. I've yet to have any of them fail on me. I know it can happen but I don't think it's that widespread.
That being said I'm all about redundancy but also in keeping things simple. I don't have a dual overflow but if I did I'd never consider two pumps. I was planning a 180 a few years back and was going to run both drains to the basement (herbie on both) and a single pump back to the tank with four outputs.
With union fittings it's easy to swap a pump out. A much more likely catastrophe is a downed power line, for me anyway. While I don't believe in two simultaneous pumps I do have two battery backups on each of my circ pumps and apex.