You made me go through my various double backers to check on this.
I can say I do not observe this in any cars I own but it does rebind me of a blankface deck in red I got some years back. The backs were many shades lighter than the standard decks I was buying at the time as to be unusable.
I think the is just a case of poor quality control and not the color.
Steve Bryant wrote:Whenever I have purchased double back Rider cards, the blues have been such a poor match for the blues used in normal Bicycle decks that they are useless as a secret tool. The reds tend to match up better.