Any data or anecdotes on spare magazine/backup gun use?

A recent post got me thinking about this. I'm not aware of any situation where a CCW holder used a spare magazine or a backup pistol.Any data on how frequent a spare magazine or backup is utilized? (Probably not)Any anecdotal evidence? It strikes me as overkill and a waste of space and weight for 99% of people. via /r/CCW http://bit.ly/2TXkSZ9