My cameras seem to run in pairs, too, though often close relatives rather than identical. Maybe just different finish color, viewfinders, etc. My rationalization is redundancy in case of loss or if one goes in for service. Also, I do like the machinery, so the choice is validated by getting another. Two is generally enough, though!
An exception was the Pentax LX... I got a pair of these for my wife's use in theatre photography, and over a number of years she thoroughly trashed them, and one was lost by the post office going in for service. That one was replaced, so when she eventually switched to digital, that newer one was still workable. Ugly, though, so when I spotted a mint LX for sale with a 1.2/50 I snapped it up. So, three, with two working!