Multi camera for stereo My question is this, say you have a scene and all the cameras are set up and all have key frames. Upon completion of the project, you decide to change the cameras out for stereo cameras to render out for 3d video, how would you go about transferring the key frames for position and rotation without the new second camera defaulting to the original key frames of the original camera. 

For example would be you duplicating the original camera then shift it to the left, rename it camera_l and the original camera_r now when you start of the animation camera_l is going to drift back to camera_r original position and rotation, how do I stop this from happening yet keep the animation data so both cameras are in sync?
You could parent a second camera to the first one. If you duplicate the first one, select the second one and in the dropdown menu of the Dopesheet (Action Editor mode) click on the X button to unlink the action from the selection. Now the second camera will follow the first one. The only problem is that the gravity center is the first camera, but maybe it doesn't bother you.

Maybe the best solution is this one: Create an empty. Keep the empty selected and in the dropdown menu of the Dopesheet (Action Editor mode) select the animation that you've already created for your camera, the animation is assigned to the empty. Now select your camera and on the right of this same dropdown menu click on the X button to unlink the action from the selection. Now only the empty will move. Parent your camera to the empty. Create a second camera and same thing, parent it to the empty. Both the 2 cameras will follow the empty.

Does it answer?