OK, I think I need some git education.

There was one section in your commit ( http://git.savannah.gnu.org/cgit/emacs.git/diff/lisp/isearch.el?h=emacs-25&id=ed19f207449c43f7f08285ada87ae7a46c61c8d1 ) which was already committed earlier ( http://git.savannah.gnu.org/cgit/emacs.git/commit/lisp/isearch.el?h=emacs-25&id=91e667692ba1362ca1334b8d58fd16c305ad5e2a ). As I am familiar with that single commit, I know that they are identical.

Also I noted that your commit has a repeat of all the backquote/straight quote changes in NEWS that happened recently.

But without this prior knowledge, how can one separate these duplicate commits from the commits that actually are new?

Also, what is the reason for such duplicate commits happening?

Apologies for this git 101 question here. Please forward me to a resource, if available, where I can understand such mega commits.

Thanks.