That is the same one that I have, and I was told it was Kwanza when I was looking to put a name on it. It's really pretty! I'm glad you found a picture because I had given up! I'm sure it's considered a ditchlily, but the one that most people call ditchlily are single.
I do wonder if it's a cross between the two. Seems like someone said that this one doesn't set seed well, or at all (can't remember now), but I'm not sure about the pollen. I had a couple of Stella's this year that stayed open for more than a day, and one lasted almost 2 full days. It's worth looking into a little further! You should try hybridizing them and see what happens!
