Duplicate tiles appear in the Zoom rooms

In Zoom meetings with 155+ participant tiles, 4 Zoom screens with 49 tiles/Zoom screen, we found that participant tiles on screen 3 were duplicated on screen 4 (the last page). Out of the 49 tiles on screen 4, all were duplicates from page 3 except for about 5 or 7 tiles that were placed at the end. These 5 or 7 were the latecomers.

This duplication only happened on the Zoom room screen and not on the Participant list.

Why does this happen?

Thanks much!