D.B.
The "updated" part with the entire answer repeated happens when you click to post and the site is slow to upload it. If you click again because you think it didn't work, it shows up duplicated. It can happen on the first post, I think. In any case, it doesn't mean the responder changed anything. It's happened to me several times, so I've just gone back in and deleted the repeat. If you edit your actual answer, I don't think anything shows up that you have edited it. I wish that the questioner would get a prompt that says "So and so has updated the response to your question." I've mentioned that in prior surveys when the admins ask what can be done to improve the site.
I've noticed the same thing about only getting old answers (2008, 2009) when you search for something - usually those responses aren't relevant to a 2016 search. I'll be interested to read what the moderators say about that.