[hmsimha]

You could mention that kind of misuse on the page where users enter their code, and suggest they don't enter their salary information unless they are aware that the code was displayed somewhere publicly (yet anonymously) in the company (like a company bulletin board or sent out to a list of company emails from a dummy address, where you can vet that the other addresses it was sent to were your coworkers). That way, no one has any way of knowing which datapoints match to which of their coworkers.