As we are identifying the various wrappers used with different card issues, we had thought that the Beatles color cards from 1964 were found with wrappers with a nickel fold, indicia on the right side of the wrapper and 4 different ads on the back. The Big Twin Chews ad version includes a black and white gum image (see below)
1964 Beatles Diary has been identified as having a wrapper with a penny fold with color gum image, indicia on the bottom and only a "Big Twin Chews" ad.
Interestingly, I recently noticed a deviation from this scheme in the collection of the always impressive Kenrich Co as pictured on the PSA site (click pictures below for a link to the collection and get ready to drool!). It sure looks to me that Beatles Color cards were also issued with the Beatles Diary wrapper variation.
This is more involved than just a different wrapper roll being used because nickel fold and penny fold packs were made on different machinery. This was probably done by Topps due to the extreme popularity of the issue and the need to increase production. Does anybody have any other ideas?