I have never heard of a Norfolk producing suckers, but that doesn't mean it can't happen. More than likely though, there were extra
seeds in the pot that germinated slower.
Caring for Norfolk Island Pines Norfolk Pines absolutely resent repotting, so there would probably be a fairly high risk of losing all the plants if you were to try to remove and save the
seedlings. Snip any unwanted trees just below the soil line and they won't come back. You might want to try leaving three trees
growing and see how they do. You can always remove the others later.
You can try to root the plants you cut out if you want. Norfolk Island Pines are one of a very few species of trees that you can actually get a branch to take root, but that produces a crawling 'fern' looking plant rather than a tree.
Propagation by cuttings