Hey Asia!
I bet the alpha does have more significance than that too. But they did originally only go by KDPhi. When they discovered that the fraternity existed, the alpha was added.
But we still just call them KDPhi on my campus. But we have KZPhi too. So it gets confusing if someone says the names too fast.
PS If I remember correctly you're colonizing an Asian sorority at your school. So if you know more about all this, cool. What I know comes from their websites and the members that I know. So I hope it's correct.