I have seen fans growing from beneath the crown and haven't formed a stolon/runner yet and have broken them off accidentally because I didn't realize they were there until I had already slammed the clump down to loosen the soil or have started prying the clump apart and break them off. The reason I think this may be the case is because on some of theses clumps with the beginning fans emerging underneath also have some of the fans with the runner attached.
I list mine as DF/2F because of this also. If I'm potting them up as double fans and I have some single fans of the same plant I will pot them up together as if a DF, but will just make sure I list as DF/2F since I won't know what is what when picking them for orders. I used to try and keep up with the ones that were actual DF and which were 2F and write it on the pot tag, but that can get to be a pain when you have a lot of pots to deal with.
