People have debated this online and parsed the laws and so on. I think asking "What's wrong with working multiple jobs" is the wrong question. Whether you call

People have debated this online and parsed the laws and so on. I think asking "What's wrong with working multiple jobs" is the wrong question. Whether you call it "wrong" or not depends on your perspective (employer vs. employee) and what assumptions you have about the obligations of employment. Whether working two jobs without disclosing that to the employers breaks the law, or violates some moral principle, or whether you consider it right or wrong, and regardless of what you think you owe your employer or how much you deliver, you have to look at it pragmatically. Most employers don't want their employees working multiple jobs. You might get fired, and in some circumstances you may get sued. If you want to work multiple jobs without getting in trouble, switch to freelancing. You will do the same work but as an independent contractor you can (almost) freely choose whom to work for, where, when, and how much. (I added "almost" because you have to avoid conflicts of interest or the appearance of disclosing proprietary information.)