Goodreads reviewers can also review on Amazon, but authors should not pressure them to copy and paste the same text everywhere.
Each platform has its own audience, and Amazon reviews should still be honest, voluntary, and written by the reader.
What Is Usually Fine
If a Goodreads reader enjoyed the book, you can let them know that an Amazon review also helps. Keep the request neutral and optional.
Some readers will post on both platforms. Others will not. That is normal.
What To Avoid
Do not tell a group to post the same wording on Goodreads and Amazon. Do not give everyone a template. Do not ask readers to post on a fixed day with matching language.
Repeated text can look unnatural.
Better Habit
Ask once, give the Amazon link, and let the reviewer decide.
A fresh short Amazon review is better than a copied paragraph that looks like part of a campaign.