It looks like the pivots are on opposite sides of the disk platters, which means that if one fails you essentially lose access to the data on that side.

That’s not really appreciably different from the same failure happening in a single-pivot drive, though it is more mechanical complexity packed into the same amount of space.

I’m not sure what the failure rates on HDD pivots are like. In my own experience the control board or motor is more likely to fail.