Most Amaryllis reproduce asexually from bulblets that form on the original bulb. Some cultivars are very slow to produce bulblets. Some cultivars produce lots of bulblets, striatum is noted for this. The baby bulbs are easily separated when they grow their own roots. My guess is that's what happened in your pot. Amaryllis blooms also self pollinate and form seeds or can be cross pollinated to form new crosses. Some cultivars are resistant to forming fertile seeds, some are great seed producers. It takes some time, but seeds eventually produce tiny bulbs. There are some posts on this forum about germinating the seeds.
