Tom, this was a Lambda Chi Alpha pin that was chained to an Alpha Delta Pi pin - obviously, the original owners were pinned. It went quite high to the bei group.
I've had similar experiences on ebay, which I've related on another thread. I saw a bracelet that was only made one year, and was identical to the one I had won for Sister of the Year and somehow lost - same initials and everythign! ! I told the other sisters bidding on it my story, and they were happy to step back. The only problem was, the picture was a bit fuzzy, and the crest turned out to be a Kappa Delta crest! The seller was good about it, but I'm still missing my bracelet.
ETA: thanks, Jacquelyn!