No, it most definitely is not! It’s considered unethical. Both schools should be able to tell you in advance which credits will be accepted. I’m pretty sure Rutgers does, and I expect Northeastern will too. Perhaps @Mom270 can confirm.
You should consider that a rejection and focus on these two schools where you’ve been accepted. Chances of coming off of a waitlist are very low. If it happens, that’s great. But don’t count on it.