When I first started researching these postcards, it was a surprise to find that Snow White and the dwarfs were represented with two different sets of illustrations, possibly one of them having been released at a later date. One group of eight cards was issued with green ink printed on the reverse side. The other batch--with different images--was produced with red ink. However, after years of searching, I have yet to come across any evidence to show that Sneezy, Sleepy, and Bashful were ever included in this latter group. Some of the red-back cards promote the children's magazine Le Journal de Mickey.
The Snow White postcards that I know to exist are shown below. The green-back series is on the left, red-backs to the right.
An example of the green ink on the reverse side. The text mentions that a free card album is available.
The red ink back.
An alternate red-back promotes Le Journal de Mickey.
Atchoum, Dormeur, Timide (green-backs only).
It seems logical to think that these last three characters would have been included in the red-back set too, but I've yet to find any mention of them online.