Generating both WEBP and not-WEBP images

I want to use WEBP images, but I'd like to fallback them to PNG, JPEG or whatever file extension it is. So I need both versions of each file, but I'm not being able to make image-webpack-loader or webpack itself to save that way. Neither searching for a way (maybe I'm using the wrong search terms?).

All I need is two different files, one converted to WEBP, and the other just optimized.

Is there any way to do this?

Thanks for the help