I will have one control rod coming from the elevator but want to hook up two servos to it. One would work but I like a backup on scale models

G'day Mate,
Maybe I missed something, but what was the question?

If you have two servos ganged on one control linkage and one fails the other will not be able to overcome the "dead" servo. You're much better off putting one servo on each elevator surface and "Y" or mix them together.