I'm not sure what more to do.
There's two ways to Save in Windows, of course.
"Save As" always warns/prompts you if you are saving to an identical filename.
"Save" always resaves with the current filename, so you already know it's writing over something. Is more warning needed for that?
I almost never use "Save", I've been doing "Save As" with a manually incremented filename for years and I've not had a problem with that.