Lot666 said: "thedrybandit said: That's true, but if they know in advance and put it in the playbill that, for example, Jeremy Stolle will be the Phantom on Thursday for both shows, as they did for today's performances, they won't put that on the understudy board."
So it's on the board and/or on a slip inserted into the Playbill; I don't understand the confusion."
I think thedrybandit is saying that Phantom in particular likes to list who is who in the playbill for each date, rather than using understudy slips for a whole week.
When there are multiple Phantoms in a week, and they know far enough in advance, it will say something like The Phantom (Monday- Wednesday) Laird Macintosh, The Phantom (Thursday) Jeremy Stolle, The Phantom (Fri-Saturday) Paul Schaefer. I can see where the OP is coming from, as it get rather mixed up when Laird is listed a few rows down as Andre, Jeremy as Passarino, etc, and their bios include their main role.