Question re E121-120 American Caramel Cards

[ValKehl]

I would appreciate the help of an E121 Series 120 set collector, as I am not one. I have these two "Sam" Rice cards that I think are authentic. The fronts of these cards appear similar. However, from looking at the backs of these cards, one appears to have been printed on a sandy-colored stock and the other on a white stock. The sandy-colored back resembles the back pictured in Rhett Yeakley's fantastic 2011 Old Cardboard Magazine article re the E121 and related sets. Can anyone (hello Rhett) confirm that two different card stocks were used to produce this set, or is one of my cards a reproduction? Thanks in advance.
Val

[FrankWakefield]

Have you illuminated them with UV light? Did the "tan" back one's front fluoresce?

[Leon]

Val
They both look real from the scan. Does the paper on the tan backed one have uneven, 90 yrs old gloss, or is it not like that? Many times the paper from new repros will feel kind of rough, not like the slick gloss that is 80+ yrs old. Specifically I don't know if they were printed on different stock but it wouldn't surprise me as some other pre-war sets were (which I have examples of)....

[ValKehl]

Frank, thanks for jogging my (sometimes pathetic) brain. I can't explain why, but I seldom think to use an UV light to test a card. But, I have just now done this, and both cards check out ok.

Leon, thanks for you input. The tan-backed card feels very smooth/slick (not at all rough), same as the white-backed card. Both cards feel the same.
Best to each of you,
Val

[glchen]

Could the tan back possibly be due to heat, moisture, humidity damage? It's modern, but I had a 1984 Donruss set that I purchased from ebay that looked like it had darkened because of this.