As I wrote, Ctrl-\ should do the trick. And it’s just not practical having to know which program applies the double pattern, and having to train yourself to not accidentally hit Ctrl-C twice.
My brush with the double-ctrl-C pattern was in a place that wrote a lot of Java. It was generally frowned on to write any code that relied on signals which windows users can't send, and if I recall, Java made it quite difficult anyhow.
Windows does have a tradition of using ctrl-c to quit though, so SIGINT ends up being one of the few that you can use in both places. It's not pretty, but giving it a different meaning based on how many times you've ordered it seems like a somewhat natural next step, if a hacky one.
