I am not clear by what you are trying to do. You can certainly have different cards registered with different programs, even if they are administered by the same company. But you can usually only have one card registered with any one administrator of the programs, so for example I can't register the same card with United, Idine, and Transmedia, since they are all the same program.

You wouldn't be able to double dip on two cards for the same meal unless you paid for it twice. You would be able to get around the one visit per month rule this way, if the cards are registered for different programs. I would expect as they merge all their data files that will go away at some point in the future.