From here at the Show I can tell you it's far from the only deck so equipped. But yes, given the choice of arms and cartridges out there, it does make switching a lot simpler, for example between a set-up optimised for LPs and one for 78s...
Wouldn't the tonearm on the left be producing a reverse stereo signal as the record would be spinning toward it? Unless the left is purely for monaural.