The 1/200 Scale Titanic and Olympic Rudder Set is meant as a direct replacement for your kit supplied rudder. This rudder has the correct shape and zinc anodes for both ships.
It is possible, that Titanic sailed with the new anodes installed after lessons learned from Olympic. But this has not been confirmed. Providing both gives the builder a choice. Or one for each kit.
Please watch this video on how to remove the rudders from their supports and receive a short explanation on the different anode choices: https://youtu.be/Yoku9_4dwzU
