Hi I have 2 Macbook Pros from roughly the same time. Perhaps 10 months apart They are almost the same. One is a 2.4 and one is a 2.56. One has the adaptor that snaps in as if from the side, whereas the other adaptor just snaps straight in. I assume you will know what i mean by that horrible description, LOL but w hat i am wondering is if the two can be used on each machine back and forth. Must one only work on one and the other, only on that one, etc since they are basically the same macbook pros?