Solve this problem by connecting to the EasyCTF shell, either in your browser or through some other TTY.
We've noticed that a list of passwords has been modified. Compare the original master_copy.txt to the suspicious.txt and tell us what the password was changed to! The files are on the shell server at /problems/same_difference.
This can be solved only with the tools available in the shell. No scripting languages are required.
There's a pretty cool Linux command called diff that might be useful for you.