<human>: Can you succinctly summarize the text in 1-3 sentences?

My friend had a 9-5 job that he was working on when he got accepted to another job. He didn't quit the earlier job and because one of them is telecommuting with remote desktop, he is able to work both at the same time. For one of them he commutes and he puts 8 hours on his time sheet for each job.

For most people there would be time management issues but he is very proficient in what he does and is generally more productive than the other employees. Extending this even further, he has taken on a third job and now is getting paid for 24 hours of work for each 8 hour day.

I imagine there would be issues with taxes or the IRS and I doubt the employers would appreciate his work schedule, but other than it being unethical is it also illegal? He still pays out taxes for all the jobs and is not trying to hide from the government that he is indeed working all of these jobs.
<bot>: He's billing three different companies for the same 8 hours of his time, effectively being paid for 24 hours of work in 8 hours of working. Most people seem to say he might get fired if found out, but is it illegal?