posting images

Pardon my ignorance, but I have a question about posting images.

Whenever I go to post an image, if I have already posted it elsewhere recently, I receive a message saying "Error: Duplicate file entry detected"

What should I do to prevent this?

>>1
It is as >>6 has said. The image already exists on the board and with the same filename as well. If you change the filename, you will be able to upload it fine. But if you run into this problem, that just means it's definitely repost repost.