still I think, we should collect them.
It's the proper thing to do, when we want to argue about certain things. To be able to make the comparison.
If we don't keep record of these, there's always a chance that somebody comes up, pointing to some examples, crying: "But here you see it - there are changes in pre-mortem works as well! They must be legit!" But when we have a full record (well, as complete as possible) of both kinds of 'changes', we can easily answer: "Yeah, but look, those changes are totally different in style than the other. It's a simple proof by demonstration."