As a Moderator, I was contact by Jeremy (Rampant Rivet) about this issue, but not having powers or knowledge of the inner workings of this website, I could do nothing and told him to raise the issue with those in charge of the site, ie Jack, Joris or Lee (Marmite). So far I have not heard anything. It seem not all posts with photos have duplication of images, so to fault find you would need to know details of how or where the photos are obtained from, ie, from computer's photo library, from mobile phone, or from one of the internet photo saving sites. This may give a pattern to the problem.
Just as a test, I have attached a photo here from my computer's photo library so will see what happens.
regards, Richard