It depends on the type of internal cable... Some have a thin tube soldered inside the main tube, to take either the whole outer all the way through, or just the inner. Others are basically a hole into the frame tube, and need the outer threading all the way through. If cable end ferrules are needed, then it would be because there is a thin tube inside to take just the inner cable. Both ends would be the same. One might be stand more proud than the other, if they weren't soldered equally. Can you take them out and post a pic of what's inside the hole? Do the ferrules butt up against something?