Yup, I agree. There are only so many Greek letters. I assumed Alpha Sigma at UW-W was the remnants of our chapter that was once there (their colors were the same as ours) until I was informed
that it was a local that had actually been around LONGER than ASA had.
And then there was the group of (extremely white) guys in the 1950 Clarion yearbook who founded a local fraternity called Alpha Phi Alpha.