Sorry you guys are at work!
I’m not going to challenge what you’re looking at, but he had no WoW previously installed as he had to wipe his hard drive & reinstall EVERYTHING. The only thing I can think of is that he was asked if he wanted to do both at the same time & he clicked yes. (He kinda has a tendency to just keep clicking stuff when he just wants to get things done lol) He’d quit playing about a year into Cata & completely removed the game once he’d transferred all his stuff to me.
As I said originally, I did remember downloading & installing Classic manually when it launched - it didn’t just appear in my drop-down.