That usually happens when you upload a file with the same identity. For example if you leave your file unchanged and it says jpeg004, then there is a strong likelihood this file will exist elsewhere. If you are uploading images, it is best to rename files with names rather than their existing file numbers they are given by cameras and computers. This happened to me a long time ago and Jeff explained that the system will upload the first use of the same identity number to subsequent uploads. Unfortunately, you cannot change it yourself now; so I recommend you email
or send a message from your account email. Good luck.