https://www.gotquestions.org/Moses-wife.html

Moses's Midianite wife was a Cushite dark skined womon Zipporah, Exodus 2:16 to 22.  She was the daughter of Jethro, who was a priest in the land of Midian, Exodus 3:1. Cushite means Black.

Numbers 12:1 leads many to surmise another Cushite wife: “Miriam and Aaron began to talk against Moses because of his Cushite wife, for he had married a Cushite.” The question of the number of Moses’ wives hinges on the identity of this Cushite, or Ethiopian woman. Is this a reference to Zipporah? Or is this another woman?

Exodus 2:22  says, Zipporah bare Moses a son, and he called his name Gershom: for he said, I have been a stranger in a strange land.

Exodus 8:2-4 says:
-Then Jethro, Moses' father in law, took Zipporah, Moses' wife, after he had sent her back, 
-And her two sons; of which the name of the one was Gershom; for he said, I have been an alien in a strange land: 
-And the name of the other was Eliezer; for the God of my father, said he, was mine help, and delivered me from the sword of Pharaoh:

Even if Moses had 2 wives, they were both Cushite women. 

Cushite:
-the historical Kingdom of Kush.
-an ethnolinguistic group indigenous to Northeast Africa Cushitic peoples.
-a biblical tribal name, see Cush (Bible).
-the natives of the Horn of Africa region, see Ethiopid race.

Cush or Kush was, according to the Bible, the eldest son of Ham, a son of Noah. He was the brother of Canaan, Mizraim (Egypt) and Phut, and the father of the biblical Nimrod mentioned in the "Table of Nations" in Genesis 10:6 and 1 Chronicles 1:8.