Donkey Kong Country Returns 3D does require two game cards for co-op

As expected, the 3DS port of Donkey Kong Country Returns (named the with “3D” moniker tagged onto the end) will require the use of two separate game cards to play co-operatively. This isn’t a shock by any stretch of the imagination, as transferring more or less the entire game (as you play) to another play via the 3DS’ wireless capabilities would be both very difficult to do, and incredibly time consuming while playing.

Via Polygon