It is an old trick used to trap the witness. They will ask the same questions and if Don Jr can not repeat exactly same answers, they can charge him with lying to Congress and perjury. It is known as process crime.
So he should NOT go..no point he already answered everything..geez the stupid Trump Tower meeting was what, 20 minutes, what more can be said about a 20 min meeting
Trump Jr. should simply say “I’ve answered all pertinent questions in previous testimony. Please refer to my previous answers if you need a refresher.” or “My lawyer has advised me that I have legal precedent to not remember or fail to recall at least as many times as Hillary Clinton has while under oath, so be prepared for a very long day.”
Why cant he just claim that he answered the question previously and they can refer to that answer ?
So, DJT Jr. would be smart to demand a copy of the transcript of his testimony to the Senate and then for each question say “what page of my testimony is that on so that I can refresh my memory?” of course he will also need a copy of the Mueller report sections where he is mentioned/quoted.