Regarding problem 2: It's hard to know what exactly you're seeing, but be aware that the output of "git log" is only pretending to be linear; it's really a tree/graph. ("git log --graph" can help, but the output can also be annoying to parse.) So when you see multiple copies of a commit "in a row", chances are that they are really present on different branches which were later merged. If they have the same commit ID, I would probably call this just a display quirk -- there's really only one "copy" in truth, but for some reason the history is confusing "git log". But if they have different commit IDs, that means (as far as I know) that someone has done a "git rebase" or a "git cherry-pick", which you didn't mention in your description.