Defense of the heart, searching for Marauding Raptor and Polyraptor

If I have defense of the heart in play, on my upkeep and an opponent has 3 or more creatures, if I sac it and search for Marauding Raptor and Polyraptor, do I choose which enters first? So I can create an endless loop of polyraptor tokens? Or do they enter at the same time, so there's no interaction?