Sorry, I did not know you knew. If I had known you knew I would have known not to mention it. But I knew that others reading the thread might not know, and needed to know what I did not know you knew but now I do know you knew.. you know.
Still there is always dos.
In a dos window use copy.
copy file.aa+file.ab newfile.
That will concatenate the two files into the third file newfile.
The default copy treats files as ascii files so for binary files you need the /B option as in copy /B. Providing of course that the two binary files are suitable for joining in this way to make a third!
You can also use type and redirection and wildcards. For more complex scenarios consider xcopy.
That is why I would use a freeware/shareware tool
Opinions are my own views, not DreamHosts'.
I am NOT a DreamHost employee OK!! :@
You act on my advice at your own risk!