It was found out that Mojang changed the cape texture for the Experience cape which caused 2 of the same duped cape to appear. Only 200 players managed to cache their cape before Mojang changed the texture. Were you one of the lucky few to get a extra cape to flex on your API site profile?
Here's the proof:
https://x.com/Fantaisiici/status/1850514575206035851
https://www.reddit.com/r/minecraftcapes/comments/1gby096/two_of_the_same_experience_capes_cached_on_namemc/
I'm mad I didn't get the cape code in my email until after it was changed but oh well.