Consistency is important. We see this in full force in the Azkaban arc.
To get 6 of yourself, starting at noon, you wouldn’t go back to 11, then “together” go back to 10. You have already created a paradox because the original 11 o’clock you was supposed to wait until noon and then go back in time. Instead, at 11, you would walk into a room with 5 other copies of you waiting, and then at noon, you and 4 of those copies would go back in time to 11.
Consistency is important. We see this in full force in the Azkaban arc.
To get 6 of yourself, starting at noon, you wouldn’t go back to 11, then “together” go back to 10. You have already created a paradox because the original 11 o’clock you was supposed to wait until noon and then go back in time. Instead, at 11, you would walk into a room with 5 other copies of you waiting, and then at noon, you and 4 of those copies would go back in time to 11.