I just watched the four part I Dream of Jeannie story Genie, Genie, Who's Got the Genie. It's unusual for a couple of reasons.
First, over half of Barbara Eden's footage has her by herself. Jeannie gets accidentally trapped in a safe in the first episode and is only freed at the end of the fourth episode. While in the safe, Barbara Eden does not appear on screen with anyone else, except in the third episode where she also plays her evil twin sister.
Second, a different actor is dubbed saying some of Major Nelson's lines. When the code for the safe is revealed, Larry Hagman as Major Nelson says the final number once on screen, but when Major Nelson repeats the full numbers, he is off screen (no lip sync issues) and the numbers are said by a different actor.
Did Barbara Eden take a holiday during the filming of this story? All of her scenes in the safe could have been filmed without any other actors needed allowing her to take a (two week?) break while the rest of the story was filmed. Is that what happened?
Was there a tie-in promotion for this episode about the combination for the safe? Were the numbers kept secret from everyone including the actors until just before broadcast?
If my guesses are completely wrong, what was the true reason for the oddities?