When doing the copy file + file command in windows XP CMD, the file with the appended information will have a box character at the end of the last line. And subsequent copy file + file commands will leave additional box characters as well.
Is there a way to keep this from occurring? Or removing it afterwards?
Use a hex viewer to see what that added byte might be. I’d guess at 0x1a, a Ctrl+Z used to indicate the end of text files. This goes all the way back to CP/M, an early operating system that didn’t have a file size property so needed a special character to indicate EOF on text files.
Use the /B option to tell COPY that the files are binary.