Hemerocallis mystery

Daylily (Hemerocallis) painted en plein-air at the botanical garden of Pisa.
There was no sign by it, which I thought was a bit odd for a flower that stands out so much, so I asked the staff if they knew the name of the variety, just out of curiosity and so I could write it under the painting in my sketchbook, but they didn't know. With some online research I found two different names for this daylily, being either 'Ruby Spider' or 'All-American Chief'.
Now, I'm not sure many other people would be interested in looking into why the same plant has two different names, but I was, and I did. Turns out it's not so uncommon for daylilies to have two different names, since the art of breeding and hybridizing them is so popular and there are so many varieties that it's hard for the authorities to keep track of them all. In this case however, I did find it slightly funny that in one year the AHS (American Hemerocallis Society) gave both of the aforementioned varieties the same prize. Surely they must've noticed at that point that they're the same, but apparently not. The two varieties also won other awards in different years.
For writing under my painting I decided to go with 'Ruby Spider', since that name seems to have been registered a few years before the other.