Here are the two stories disentangled, with the harmonizing glosses removed:
P: Korah son of Izhar, the son of Kohath, the son of Levi, and 250 Israelite men, well-known community leaders who had been appointed members of the council, came as a group to oppose Moses and Aaron. They said to them, "You have gone too far! The whole community is holy, every one of them, and Yahweh is with them. Why then do you set yourselves above Yahweh's assembly?" When Moses heard this, he fell facedown. Then he said to Korah and all his followers: "In the morning Yahweh will show who belongs to him and who is holy, and he will have that person come near him. The man he chooses he will cause to come near him. You, Korah, and all your followers are to do this: Take censers and tomorrow put fire and incense in them before Yahweh. The man Yahweh chooses will be the one who is holy. Each man is to take his censer and put incense in it -- 250 censers in all -- and present it before Yahweh. You and Aaron are to present your censers also." So each man took his censer, put fire and incense in it, and stood with Moses and Aaron at the entrance to the Tent of Meeting. When Korah had gathered all his followers in opposition to them at the entrance to the Tent of Meeting, the glory of Yahweh appeared to the entire assembly. Yahweh said to Moses and Aaron, "Separate yourselves from this assembly so I can put an end to them at once." But Moses and Aaron fell facedown and cried out, "O God, God of the spirits of all mankind, will you be angry with the entire assembly when only one man sins?" Then Yahweh said to Moses, "Say to the assembly, 'Move away from the tents of Korah.' " So they moved away from the tents of Korah. And fire came out from Yahweh and consumed the 250 men who were offering the incense. Yahweh said to Moses, "Tell Eleazar son of Aaron, the priest, to take the censers out of the smoldering remains and scatter the coals some distance away, for the censers are holy, the censers of the men who sinned at the cost of their lives. Hammer the censers into sheets to overlay the altar, for they were presented before Yahweh and have become holy. Let them be a sign to the Israelites."
JE : A few Reubenites, Dathan and Abiram, sons of Eliab, and On son of Peleth, became insolent and rose up against Moses. Moses asked Dathan and Abiram, the sons of Eliab, to come to him. But they said, "We will not come! Isn't it enough that you have brought us up out of a land flowing with milk and honey to kill us in the desert? And now you also want to lord it over us? Moreover, you haven't brought us into a land flowing with milk and honey or given us an inheritance of fields and vineyards. Will you gouge out the eyes of these men? No, we will not come!" Then Moses became very angry and said to Yahweh, "Do not accept their offering. I have not taken so much as a donkey from them, nor have I wronged any of them." Moses got up and went to Dathan and Abiram, and the elders of Israel followed him. He warned the assembly, "Move back from the tents of these wicked men! Do not touch anything belonging to them, or you will be swept away because of all their sins." Dathan and and Abiram had come out and were standing with their wives, children and little ones at the entrances to their tents. Then Moses said, "This is how you will know that Yahweh has sent me to do all these things and that it was not my idea. If these men die a natural death and experience only what usually happens to men, then Yahweh has not sent me. But if Yahweh brings about something totally new, and the earth opens its mouth and swallows them, with everything that belongs to them, and they go down alive into the grave, then you will know that these men have treated Yahweh with contempt." As soon as he finished saying all this, the ground under them split apart and the earth opened its mouth and swallowed them, with their households and all their possessions. They went down alive into the grave, with everything they owned; the earth closed over them, and they perished and were gone from the community. At their cries, all the Israelites around them fled, shouting, "The earth is going to swallow us too!"