Two heaps - Probably placed one on either side of the gateway, to strike terror into the partisans of the late dynasty as they passed in and out of the town.
Related Commentaries of 2 Kings 10:8
2 Kings 10:8
8 And there came a messenger, and told him, saying, They have brought the heads of the king's sons. And he said, Lay ye them in two heaps at the entering in of the gate until the morning.