This is a new type of amaryllis which the dutch call "Klister" because it grows as clusters of bulbs.  It has fewer stems and flowers per bulb, but many stems and flowers with each cluster.  Some say it grows well outdoors.  Obliviously by its very nature it multiplies easily on its own.  We believe it is Lovely Garden (no longer available commercially from the Netherlands.

The bulbs for sale here are 2-3 inches or so across with smaller new offsets forming.