Yes, they all come out of that one gourd. That's quite a lot of seeds. I'm estimating that there's about 400. I plan to dry them, save a few for myself, sell a few, and give the rest away. Since I have several more gourds on the vine, there will be plenty of seeds to go around.
This gourd plant is the only one on my farm, in fact, the only one I'm aware of anywhere near me. So I'm assuming it's most likely been pollinated with itself. That fact should help make the next generation similar to the parent. But since I don't know the parentage of the mother plant, there's no guarantee. Yes, the mother plant is a volunteer that just showed up here out of the blue.