Why do we find Jesus having two names given to him in the same discussion to Mary?

Matt 1:21 "And she will bring forth a Son, and you shall call His name Jesus, for He will save His people from their sins."

Matt 1:23: "Behold, the virgin shall be with child, and bear a Son, and they shall call His name Immanuel," which is translated, "God with us." (this is quoting the prophecy fulfilled of Isa.7:14)

Matt 1:25 and (Joseph) did not know her till she had brought forth her firstborn Son. And he called His name Jesus.”

Names and titles in the Greek language are indistinguishable. Both names can be applied to the same person just as in the Old Testament God had over 70 names applied to him- it is because  each give a characteristic of his nature. One identifies who He is (Immanuel), the other is the name he will bear in the incarnation, identifying His mission, what he will do as God in the flesh.

It has been nearly 2,000 years since Jesus ascended  and we don't know the time of when he is to come back. We do know that he will come with a new name.   Revelation 19:12- 13: “…He had a name written that no one knew except Himself. He was clothed with a robe dipped in blood, and His name is called The Word of God.” V.16 “And He has on His robe and on His thigh a name written: KING OF KINGS AND LORD OF LORDS”