I can't think of a company that would not fire a new hire who was still working at his/her previous employer. Nor can I think of a company that would agree up

I can't think of a company that would not fire a new hire who was still working at his/her previous employer. Nor can I think of a company that would agree up front to let a new hire do this. Why would you hire people who screw over their employers? They might do the same to you one day when they have decided to leave. This is a great way to start out with two jobs and end up with zero.