Not sure how big your twin is, or which size/type engines you have, or how much room you have, .... but I am setting my twin up with 2 seperate servos. I am also going to use a Matchbox. With the Matchbox, you can use only a single channel on the radio, and fine adjustments (if needed) can be made individually to each servo.
Ensure that you use identical servos and try (if possible) to use identical size/type hardware.
(PS: The MSA-10 is Futaba's version of the Matchbox). Bob