Hi Cagri,
This CompilerConfiguration object give the details about the default compiler used by the mex command.
You can check for other MexOpts xml files available on your , you can run the "mex -setup C" command. It will show you the different MexOpts files available based on the installed compilers for that language as well as the command to set it to default. I'm not sure how the location of this file is decided, but it must be likely based on how the compiler was installed, whether through MATLAB support package or directly on your system.
If you do not see the same MexOpt file as your colleague, please remove the given compiler and do a reinstall the same way on both systems.