Vilna Gaon: Berachyah and Elkanah were Leviyim; they were gatekeepers for the Aron. Two Kohanim, Oved Edom and Yechiyah ¹ , were also gatekeepers for it. Everyone listed here was a gatekeeper; some were further inside (closer to the Aron) than others.

Malbim: The Leviyim went in back of the Aron, and seven Kohanim went in front of the Aron with trumpets, like the conquest of Yericho, in which seven Kohanim went in front of the Aron with Shofaros. Berachyah and Elkanah went in back of the Aron, and separated the Leviyim from it, lest they approach it. Therefore, they are called gatekeepers for the Aron. Two Kohanim, Oved Edom and Yechiyah, went in front of the Aron, and separated the Kohanim from it. They were called gatekeepers for the Aron in front.