I googled MGSS and there are images that look like both of yours. I would guess that the one odd ball is the incorrect plant, based on statistics. I would wait until both have matured seeds, and use that as the deciding factor. Whether you have the actual variety or not only matters if you were hoping to save seeds for trading with others. Both types of seeds will give you beautiful plants, obviously, and all of the seeds will be equally edible to both humans and critters.

Martha

Mg stripe has yellow centers so it's not the second photo, but the first is actually kind of small for a mammoth so is question that one as well. Usually the seed heads are at least a foot across and there's only one main bloom, no side shoots!

My mammoth grey stripe looked like your top one. This year my sunflowers aren't very big. I imagine it was the weather. They are shorter by 1-2 feet and the heads are going to be smaller. My big ones aren't blooming yet, just the small branching ones.

They are both beautiful, though!

Heidi