Oh yeah, the NLRA. As opposed to just quitting and finding a better job? Getting the government (or unions) involved in variably makes a situation like this worse. Just walk away.
Now if you feel that the other employee is being under compensated, and you are getting too much, then that may work out. Or, it may be better to work somewhere else that has more money to spend on employee salaries. But the point still stands, that just because something is legal for you to do doesn't make it a good idea to exercise your rights in every situation.
Companies not complying with labor laws should be avoided, for your own protection.
It's that simple.