These are growing off the roots of the original plant - you can only grow them on separately if you get a good piece of root with each one, often difficult because the new growth tends to arise at the base of the old trunk. If you leave them in place, each one will continue to grow and form a trunk eventually - provided the winter doesn't get them this year. If you can't get roots with any of them, just remove the ones you don't want - but wait till spring to see what's left.