Like others, I have different cards registered under different airline programs. I just noticed that some restaurants show up on some airlines' sites, but not on others. I also noticed that the differences occured mostly in "new" restaurants to Rewards Network. But since (I assume) all the sites are administered by Rewards Network, why would they have different databases?

Has anyone actually used different cards (registered to different airlines' programs) and received mles on one card but not the other?