Is this file on a PC or other system?
If it is for a PC you can create a batch program with a text editor.
simply change to the dir where the file is stored.
then enter the file copies.
copy myfile.txt myfileA.txt
copy myfile.txt myfileB.txt
copy myfile.txt myfileC.txt
Then save as a batch PGM for example MYCOPY.BAT
If this is to be done elsewhere we need some more information.