Image doubled?

Hi all,

I just installed your plugin and, once I tried to verify the output with GTMetrix, I noticed this alert:

The following resources have identical contents, but are served from different URLs. Serve these resources from a consistent URL to save 1 request(s) and 532.3KiB.

http://www.recensione.biz/wp-content/uploads/2015/07/AAA-recensori-cercasi-800x500.png
http://www.recensione.biz/wp-content/uploads/2015/07/AAA-recensori-cercasi-800x500.png?resolution=592,2

So, it seems as the plugin doubled the images: one scaled and one original.
Do you think it could be considered as an issue? How can I solve it?

Thank you in advance for your kind response.

https://ww.wp.xz.cn/plugins/adaptive-images/