I know literally nothing about apples, but ive listened to some of the orchard people around where i live (so this information may or may not be accurate but):

supposedly cross pollinating between apples is actually vital to how apples fruit. and after a decade or two of careful cross pollinating (usually with honey bees) you can have a new apple cultivar

but also apparently a common way to pollinate apples (and probably keep the same kind of apple) is to graft a cutting of the same kind onto the tree and pollinate that way?

again all my knowledge comes from rural farmworkers who may or may not know how the actual process works and I'd be delighted to know how it actually works

edit: also this picture was taken at a harvest fest-type thing so the blurb might be just for visitors and not reflect how things really go