Both. C can run a batch to create the 2 versions of the animation. If you create the animation as sequencial TIFs, (or the still image that supports alphas of your choice,) then run the second animation of seq. stills, then in PS figure out what you need to replace the alphas, create the action, and let it fly. If you practice on a single frame, you should be able to figure out the steps needed. From each pic, copy the alpha channel to the clipboard, then remove the alpha from the other clip and paste in the new one. Close each file, saving each to a new folder. Creates a lot of pics, but it should work fine. Or, if you use rendered animations, then in your video editer program, tell it to use the alpha from a one rendered animation to control the other. I'm sure it works in Premeier. I can do it in FinalCutPro. Good luck!