If IT doesn't want to do anything with the feedback, that's their problem. I wouldn't change anything about this, because it looks strange to the end user. For one article he does needs to provide feedback and for the other he doesn't. Just keep the user experience the same and let the departments responsible for the feedback do what they want (and let the all over knowledge manager provide feedback in department meetings: "users using the HR KB are very happy and users using IT are thinking the worst about the department and 'hey...' that's because HR does something with feedback and IT doesn't care about its users").