It's immoral because to be hired for a 40/hr full time job by 2 companies at the same time, you'll need to lie to both companies, representing to both that you're working full time, while in fact you aren't.
And presumably the lies aren't limited to the interview process. You'll probably have to lie on a daily/weekly basis to keep up the ruse (for example, what will you say when both companies want you in a meeting at the same time?)
And presumably the lies aren't limited to the interview process. You'll probably have to lie on a daily/weekly basis to keep up the ruse (for example, what will you say when both companies want you in a meeting at the same time?)