I wrote a file called cp.bat and the content of this file is: DOSKEY cp=COPY $* copy. I saved this file in c:\users\myname\aliases. I also added this path to my environment so cmd can execute it.
When I now type cp in my cmd the output is a strange character for the c in cp.
I need this script to work because I want to install chicken scheme eggs on my machine, but the chicken-install command executes multiple cp commands and those are not recognized in the cmd.
I also tried to alter the build script of the eggs, but it gets newly generated everytime I call the chicken-install command.
It would also help if someone could explain me how to install chicken eggs on a windows machine correctly. I feel this workaround shouldn't be necessary. Thanks in advance.

Like Magoo mentioned:
The encoding was messed up and it was set to UTF-8-BOM, so I changed it to ANSI and it worked flawlessly.