But since this was basically a question from the 2019 paper, do you think it would still come up?
The version of this question that was included in the 2019 paper is as follows:
Who was more significant in ending the Cold War: Reagan or Gorbachev? (25 marks)
The main difference between this question and that of the sample Modern History HSC paper is that the sample question encouraged a response that is more focused on the Soviet policies under Gorbachev while still requiring that you cover one or more of the points highlighted above, whereas the 2019 question implies the need for a direct comparison between Reagan and Gorbachev with respect to ending the Cold War.
To answer your question, it is highly unlikely that 2 identical questions are included in different HSC papers. However, there may be variations of a particular question, as seen with that of the sample paper and that of the 2019 paper. If this ends up being the case, you will need to ensure you address the specific needs of the question without being influenced by other versions of the question that you may have attempted prior to the exam. Additionally, as mentioned by vishnay, it is less likely for a particular component that was assessed in a recent HSC paper to be assessed in the subsequent paper.