Mississippi
tattooballooncommitteekeennessraccooncoffeebookkeeper
vacuum and continuum
balloon coffee
Well, there's probably more than three. Right now I could only think of "balloon" and raccoon though, assuming that you meant those double letters have to be next to each other.
Multiplication
Mississippi
tattooballooncommitteekeennessraccooncoffeebookkeeper
vacuum and continuum
bellhop
quizmaster
"a" & "b".
bellhop
quizmaster
balloon coffee
bellhop
quizmaster