Okay, so lets assume we can only register one card.
We can still get multiple entries by making purchases as multiple stores, no? Or, by sending in a postcard (or maybe even a few) to each store, no?
See
here under "Free Participation"; In the middle it says "Limit one (1) request per outer-postmarked envelope."
I wonder if that is la'afukei two people entering with one envelope, or one person with two entries (albeit one registration) entering with one elvelope...