P: Saving copy not saving over jpg file

Having the same problem as Steven. I created a layered photoshop image and save it as .psd. Once finished I flattened the image and did a "SAVE AS" and chose JPEG. The file extension never changed to .jpg. It kept the .psd extension an over wrote my layered file. Which now can not be recognized by photoshop when I try to reopen it. have to start from scratch. 

It's not overwriting an existing jpeg when saving with the same file name, it's adding 'copy' to the end of the file name and saving a second jpeg file. It will however, when saving for a third time automatically choose the 'copy' version to overwrite, but brings up a new pop-up box after the normal 'do you want to replace...' warning, which seems to double check that you want to replace it (adding even more time spent saving).

Not sure I understand this. The problem was that Photoshop would not update the file extension if you save a file in another format, so for example you have a tiff file now and you choose save as jpeg. That will obviously always save a copy.