MurphyWasRight, "There may be confusion here between time stamps,synchronous sampling and lower than nyquist sample rate artifacts," is right on the mark. Our good friend Nyquist is what syseng68k was forgetting about. The tick marks for left and right elevator are at different
times. You MAY be able to put the two streams together and derive what the elevator was really doing at the time. There will be some lag between their actuators. So some difference may be visible. Calibration tolerances may lead to further differences.
In this case if you simply draw the line through both sets of points you get a fairly decent picture of what the elevator as a whole was doing. And it's pretty clean about it.