I just wrote about this in "Penny Lane," but I found an-other instance of an instrument doubling a vocal part in a Beatles song. This time, it's guitar during the second half of the first two verses of "Lucy in the Sky with Diamonds" ("Cellophane flowers of yellow and green..." and "Newspaper taxis appear on the shore...").
Additionally, there's a vocal and guitar glissando on the "away" in "Waiting to take you away," suggesting the distance to which you'll be taken.
