If the two elevator servos you are using match within mfg specs, there is a problem either in your mechanical setup or in the way you have the programming setup in the radio.

The key things are to be sure that your subtrims are still set at zero to start, your ATV's are the same (ideally at the highest number possible) and your servo arms are in the exact same position relative to one another. If the servos are mounted on the fuse side the servo arms should be 90 degrees to the front to back centerline of the elevators at neutral and if they are mounted to the elevator halves they (the servo arms) should be parallel to the hingeline. Since this means that the servos arms are 180 degrees opposite of each other so one or the other is going to be about 1 spline off of center. On the servo that does not line up regardless of what spline you put the servo arm on, once you get it as close as you can get, use subtrim to get it in the right position if moving the servo arm one spline will not correct.

Also, be sure that you are using one of the Pmixes that are designed to trim both surfaces when you trim the master elevator. I think this is 4 and 5 or 5 and 6 I cant remember for sure.

One you get the servos moving in perfect harmony as mentioned above then you know that all thats left is mechanical adjustment. Here are the very simple KEYS to having even throws.

1. Control horn pivot point holes (the one you attach the pushrod clevis to) must be dead center over the hinge line or at least the exact same relative to the hinge line on both elevator halves.
2. Control horn pivot point holes must be the exact same height from the centerline of the control surface (hingeline). I do not always trust the top of the elevator surface as sometimes one side has been sanded thinner than the other.
3. Control horns are both positioned the exact same distance from the side of the fuslage.

Once you get all that setup, then LEAVE THE RADIO ALONE and do this,
Tape the elevator halves so that they cannot move. I usually tape at the tip or tape the counter balance.
Now turn on the radio system and with the pushrod connected at the servo adjust the length of the pushrod by turning the clevises until the control horn clevis will connect to the control horn without binding. Once the length is adjusted properly the clevis will easily fit right on.

Now remove the tape and test. If you followed these instructions the throws will match everytime.

I have probably setup 100 airplanes in the last year and this works every single time no matter what plane and what radio. Its all in the setup.