1: You are NOT helping them get anything. Private sectors jobs are not union jobs where everyone starts at the same level, gets the same raise and has the same benefits. If an employee feels they deserve a raise, they should present an argument based on their own merits, not because thats what someone else is making. There could be any number of valid reasons why one person makes more than another including when they were hired (were they replacing someone who was making even more? Were they hired at a time when the company was able to afford to give higher salaries? did they come into the company with more experience? in a smaller company, was the other person hired at that salary as a favor to their uncle joe? these are just a few reasons why 2 employees who perform the same function might have different salaries)
2: You are creating resentment directed towards you from your manager/boss. For starters, you show that you cant exercise proper judgement by sharing what the company considers private information. How will they feel about sharing other company info with you?