Issue with merging several project from Pix4DCatch

Hello. Currently, I am working with Pix4DCatch + Iphone 14 Pro with viDoc RTK on a large area. I divide the large area into several small areas. I scanned all areas within 6 days. During the data processing, I followed the instructions provided in this Pix4DMatic - merge webpage. The steps that I do: [Each small area project] Import image → Import GCP → Mark GCP scanned in the small project → Calibrate → [Merge small project] Create new project → Merge project → Mark ‘Merge identical camera’ if it can be checked. If it can’t be marked, I allow the project to have 2 cameras. Although the image was taken from the same device → Re-optimize → Dense and depth point cloud computation.
The problem I face is the final dense point cloud has 3 surfaces instead of only 1 surface in the same area. Do I make any wrong steps? Does the problem comes from the ‘Merge identical camera’ option cannot be marked? I attached an image of example problem (cropped area is marked with red rectangle)

Thank you.