On the Wicked CD, it sounds like the lover is sung by Andrew Palermo to me, doesn't sound like Joel Grey as much.
I saw Wicked on tour in March and Andrew Madsen played the lover but he was not on as Fiyero, so they must have changed it now. I can't remember who played the role other times I saw the show. James Brown III played it when Ben Vereen was the Wizard.
I have actually seen productions of Joseph where Jacob has played Pharoah or Potiphar and the Pharoah doubling worked especially well!
Dean: Can I tell you something?
Lorraine: That depends on what it is.
Dean: I think you're really really pretty.
Lorraine: (after a pause) Ok, you can tell me that.