The fact that you hide it from both employers is what's wrong with it. It's unethical, even if it's not illegal, especially because you're likely doing both job

The fact that you hide it from both employers is what's wrong with it. It's unethical, even if it's not illegal, especially because you're likely doing both jobs during the same hours. It's not like you do one 8 to 5 and the other 6-2. When an employer hires you "full-time", they're asking for your full and complete attention. I'm not saying they own you or that you should work more than what you're getting paid for. But you're short changing your team, your manager, and the company who is trusting you. I take it you're not a manager/leader. If you were, you'd get this. Imagine every member of your team double timing. Now you're left with a bunch of people half-assing it. It's deeply demoralizing. And without ethics, you're just a cheat. It's no different than cheating in an exam. If you want to earn more, start a business. Become a consultant. Learn how to make yourself more valuable. Don't cheat.