Overwrinting as saving the (unwanted) changes over the file.
I know the workflow on these collaborative online tools is like that. I also don't see a reason why an offline tool can't be like that, but I think turning it on by default would cause more bad surprises for people who don't expect it to do things unannounced and without asking.
I guess this is something the program could ask on initial startup and make the editor UI very clear on what the state is.