It sounds to me as if someone may have artificially marked the hedgehogs which are visiting you.
It is a sad fact in this day and age that some humans feel the need to artificially mark hedgehogs, often for their own convenience, to fit in with their own lifestyles. In most cases this in no way benefits the hedgehog. On the contrary, it can potentially be detrimental to the hedgehogs by encouraging them to become habituated to humans and, potentially, interfering with their social interations, including reproduction, because of the unnatural smell of the marking. It can also get into other hog’s eyes, if they biff them, or onto hoglets, if it is a female which is marked.
Hedgehogs are wild animals and are best allowed to remain wild animals. Humans should only interfere with them if it is for the hedgehog’s benefit.
Far better to leave the hedgehogs to be their wild, natural, beautiful selves. It is possible to identify hedgehogs from their natural markings. This is probably easier if you see them in real time, rather than on film, but even on film, there are distinguishing natural features on most of the hedgehogs. I would encourage you to take the time to identify them the natural way. This can be more rewarding and has the benefit that you can identify the hedgehogs year after year when they return from hibernation. It also has the benefit that hedgehogs are left in their natural wild beauty, so that everyone else can also enjoy seeing them as they are meant to be.
Good luck to you and the hedgehogs.