Applying ED2 to a school where first ranked student at high school was accepted ED1

Depends much more on what that ED1 school is and whom they have accepted from the school in past (ie what rigor, rank, general EC type kid gets in Ed1 or 2 from there). If in the past few years admits have happened regularly with kids similarly-profiled to yours, then they have a great shot! The fact that the school already has one from the HS isn’t relevant.