This document explains how to copy questions from one quiz to another quiz in the same course.
Edit the quiz that you want to copy questions into. Then perform the following:
Select the Properties tab, if not already selected.
Press the Add/Edit questions button.
Press the Import button near the top.
Under "Import Source", select From an Existing Collection.
Under "Source Collection" choose the quiz that contains the questions you want to copy over, or select the question library if you want to add some questions from there.
Under "Source Section", choose Collection Root or a question folder if the quiz questions have been placed in section folders or you selected the question library.
Check the questions that you want to copy.
Press the Save button in the lower left corner.
To add more questions from another quiz or the question library, repeat steps 3 - 8 above.