Regenerated thumbnails

I changed thumbnail size and then regenerated a couple pictures. But then I realized I didn’t want to do that so I went back to the original code and then deactivated the plugin. But now I end up with 2 pictures of the same picture in each post. What happened? And how do I get rid of it? My site is mashedmush.com

https://www.ads-software.com/plugins/regenerate-thumbnails/