My sister can unlock my iPhone with her fingerprint

Hi Mr. Cook, My name is Hans H. who come from Taiwan. I’m a teen-age student. My father bought iPhone-13 Pro and release iPhone 8+ to me. I’m glad to have iPhone in my life. But I found a Finger Print recognition issue on it recently. I’m surprised that my sister can login even she doesn’t set finger recognition. As I know, everyone’s fingerprint is unique. I and my sister are glad to be research object to you/apple team for further clarified. BTW, attached the video for reference. Thanks! Hans

[Edited by Moderator]