Server: PageSpeed module installed - GTMetrix

If you have PageSpeed module installed on your server, and your GTMetrix pagetest shows you an error about "Serve resources from a consistent URL" because of some duplicated content, then here's what you should do.

Open up your Pagespeed.conf file, and add this line:

ModPagespeedDisallow "http://yoursite.com/your-image-folder/slider-images-folder/*.jpg"

Which will exclude every jpg images from your /your-image-folder/slider-images-folder/ resolving the problem.

Of course, you can exclude exact images, if needed, like this:

ModPagespeedDisallow "http://yoursite.com/your-image-folder/slider-images-folder/my-slider-image.jpg"
ModPagespeedDisallow "http://yoursite.com/folder/img/img2.png"
ModPagespeedDisallow "http://yoursite.com/images/picture.jpg"

Which will exclude my-slider-image.jpg, img.png and picture.jpg from the set folders.