Seeing what happens during the period the Two Witnesses testify, which will be the last half of the Week, or 3 1/2 years, they can't be any other than Moses and Elijah.
Elijah will more than likely shut up the Heavens that it will no longer rain, and there is to be a Fire Test such as he did on Mt. Carmel in the days of King Ahab.
As the Plagues that were poured out on the Egyptians will be similar to those pour out in Revelation, by who other than Moses.