Star Wars is two distinct trilogies: The "Original Trilogy" (OT) and the "Prequel Trilogy" (PT). Frank Oz was in the entire PT, but not in the entire OT. Hence he only scores one trilogy out of it. Anthony Daniels, however, scores two trilogies as he is in all six (albeit only as voice in TPM), but has failed to turn up in a third trilogy, so he is no friend of mine.
