By “different in each case” I’m assuming that means that the doubles in each light are different, not that all doubles occur only once. If that’s right then heehee isn’t allowed in 2. I have 26/34 as a possible answer, but if that is correct then 30 is
-O-HE-N, and I can see nothing which works.
And, despite it being a common phrase, 33 isn’t in BRB, so that’s another error from Doc.