Embrilliance Essentials for Mac (at least on Lion) will overwrite an existing file with the same name without any warning. I ran a test on a Mac and a PC to confirm. I can open a file and save it to the desktop. I can open a different file and save it to the desktop using the same name as the previous file. On the Mac, it replaces the first file with the second - no error message or warning. On the PC, it tells you that the file already exists and asks if you really want to overwrite it. No other Mac program allows this. I have many backups of all of my files, but I see this as a real danger.