OK, problem solved. The program gives each image a unique name consisting of Year + Month + Hour + the original image name. When images are uploaded using iOS every image has the same name - "image"! So provided you waited longer than an hour your second image name was different from the first. This doesn't happen with a PC where each image retains the name the camera gave it or one you gave it. I have now added minutes and seconds to the image name so unless you upload the second image less than one second after the first it will have a unique name! Apologies for the oversight on my part Nick