@audra_agnelly ...
I know your post was from a couple years ago, but was this for Classic Quizzes or New Quizzes? I just tested this out in my own sandbox course, and I could not duplicate your scenario where you say the ID numbers do not change. I used the "Copy to..." option within the "Quizzes" page to make a copy of a Classic Quiz. The original URL was something like:
After I used the "Copy to..." option to make a duplicate of this Classic Quiz in the same course, the new URL was:
In the second quiz, I added the word "red" to a question, saved the question, and saved the quiz. I then looked at the first quiz, and I did not see the word "red" in that same question.
When I used the "Copy to..." option for a New Quiz in my sandbox course, I also got a different ID number in the URL.
Anyway...that was my experience in my own testing. Hope this helps.