I have two identical models, but with different animations. How do I append all the frames from one to the other? I tried exporting and importing, but I coudn't export more than one frame at the time. Can anyone help me?

You can use the import and export features in MED.
Open one model and export -> export model to 3ds, and you have all frames individual. Next, open the second model, go to import -> import append frames from 3ds, select all the frames you want and that´s all.
Hope it helps.

Thank you very much. Works like a charm