Intrada's "Robocop" kept the same cover, though they did double duty by including the original cover and a new cover for Leonard Rosenman's "Star Trek IV: The Voyage Home" of which the inlay booklet could be flipped over (of course this has happened many times).
Most of the time, the expansions have different covers to distinguish them from the originals (albeit, as has been mentioned, often with the original cover as a flipper). There are times where this isn't the case, but more often than not the art direction for the expansions tends to revolve around different artwork than the original album. Exceptions are obviously when either there is a paucity of artwork, or if the artwork itself is too iconic (e.g. Conan the Barbarian, Star Trek: The Motion Picture).
