Ivy. No “e.” And Northeastern is not an Ivy League School.
Different schools have different policies. You really need to look at each school’s requirements. Some require all scores; some don’t. Regardless, they will generally still look at the best scores, so I would not be too concerned about it. Personally, however, I see no purpose in him taking the SATs as a soph anyway. The PSAT would have given him the real-life testing environment, and he can do practice tests on his own.