It is not unusual on a two-door refrigerator for one door to pop open when the other door is being closed. This means there is a good door seal. The compartments are connected by air channels to allow air to pass between them. Closing a door shut forces air from one compartment into the other, which can push the other door open.  This is normal if the door closes again on its own. It is not normal if the door stays open.

If the freezer door stays open, check the leveling legs and may sure the refrigerator is raised slightly in the front. Leveling instructions are in your Owner's Manual.