To avoid this, plan ahead. Prior to uploading, rename your photo to a guaranteed unique name: use your forum name (e.g. 49er), add the date, 20120127, and then add the rest of the picture name.
E.g. 280SL.jpg (which already exists) becomes 49er20120127_280SL.jpg
You'll have no problems no more. And no, this is regrettably not easy to fix, and I have looked into it in a lot of detail.
Peter