TL;DR: Stop doing that.
First, Hugo doesn’t support that. My suggestion would be to move your images into the static/images/ folder of your Hugo project, remove the mod_rewrite junk from apache, and be done with it. You may want to reverse the rewrite logic for a spell so that all the search engines can update to the new location, and then remove the rewrite rules.
Second, I’m really curious why in the world you would want to do such a thing in the first place. You’re basically forcing two HTTP requests for every image on your site, which wastes bandwidth and creates latency.