The only boat I sailed with twin rudders was an old open 60. It never seemed to steer very well down wind
, I suspect because the windward rudder alternately bit in then cavitated as the boat rolled.
She would start to round up, the windward rudder would cavitate and stall and she would need a lot of helm
to bring her back down, then as she leveled up she suddenly would spin around into a gybe if you weren't real quick pulling off the helm
you just applied seconds before to control her.
The rudders were also a real pain sticking out the side like that, catching seaweed and every chunk of ice that went past. They were also extremely vulnerable if the boat ever grounded. And they caused a lot of friction in the steering