The multiple groups are automatically determined by Substance Sampler. When two images are too different from each other (pixels, focal, etc.), Sampler seperate the images in Photogroups, but this doesn't affect the triangulation.
However, it can be an information of why a scan fails. If (as in your example) all the images are in seperate photogoups, this means that all images are too different from each other, and the process will probably failed.
That being said, from the images in your screenshot, I guess the Image to Material would be a more appropriate workflow. The 3D capture is more dedicated to scan objects, not surfaces.
Regards,
Cyril Dellenbach (Micro) | QA Support Artist | Adobe