Many...if your on a mountain and your touchscreen is literately frozen you wish you have a other one...also if you have to trust in a technology you better have 2 devices or a additional map and a compass.

I heard people do this with expensive cameras and equipment. Instead of renting, they can buy one for a vacation, then return it when they get back home.

It was a reference to bygone days, but the practice wasn't that uncommon in certain Western countries...