<p>Clearly your reading comprehension needs work. I said that Duke can easily get its yield up to 55% by admitting 50% of its class (the same proportion as Penn) in the ED round. Duke already wins cross admits with Dartmouth, Cornell and Chicago according to Parchment.com and is almost dead even with Penn, Brown and Columbia. As someone who was admitted to Princeton, I think I am better qualified to comment on Duke vs the Ivies than you are.
Getting the yield up to approximately 55% would not require an increase in the RD yield rate. It is just a question of mathematical manipulation. Increasing the RD rate is where things get tricky.</p>