re: Working 2 jobs at once - is this wrong?

Early prediction:
Invariably, the new job will require your idiot friend to go to the home office within the first month or so for some kind of HR Orientation/Corporate Culture/Company Procedures and Policies seminar that takes all day. That'll be the day there is a crisis at his "old" job that he can handle because he's sitting in a lecture that may or may not include a segment on ethics. Then, as you say, hilarity ensues ... to be followed shortly by unemployment.

Plenty of people get away with double dipping for a week or two when leaving one job and starting the next, but I'd think it rarely if ever works for a couple of years.