It is your problem no? If someone takes 2-3 jobs BUT still producing enough, what does it matter? If a company has a problem with it and punishes everyone, again, it is a 'you' problem.

If I am laid off (company doesn't give a shit about me), will you give me part of your salary? No right? So why the f should I care if my actions (assuming they are legal) affect you? 2 salaries? Yay, I will get to retirement in half (or less even) time. Have a problem? Well change companies or do it the same. If your company punishes everyone for a couple individual actions, they don't know how to manage people or even who is working two jobs, just a suspicion. Change jobs, but let the people that can and prefer to work 2/3 jobs, finally had an opportunity to get ahead alone. It is your problem, not theirs