There are many individuals in the New Testament who appear to have two names.
St. Matthew is one example, as he is also called "Levi" in the Bible. Some scholars believe that the tax-collector simply had two names, one in Greek (Matthew) and the other in Hebrew (Levi).
This is very possible, as scholars point to Simon (Peter) and Saul (Paul) as similar examples that don’t signify a name change, but the existence of two names in two different languages.
John Mark
In the Acts of the Apostles, there is a reference to a "John Mark":
When he realized this, he went to the house of Mary, the mother of John who is called Mark, where there were many people gathered in prayer.
St. Peter, however, only mentions him by the name of "Mark."
The chosen one at Babylon sends you greeting, as does Mark, my son.
Most scholars believe that John Mark is the same as Mark, who is the writer of the Gospel of Mark.
The Catholic Encyclopedia explains that this name may be on account of the need for a Greek and Hebrew name:
To the Jewish name John was added the Roman pronomen Marcus, and by the latter he was commonly known to the readers of Acts (15:37, ton kaloumenon Markon) and of the Epistles. Mark's mother was a prominent member of the infant Church at Jerusalem; it was to her house that Peter turned on his release from prison; the house was approached by a porch (pulon), there was a slave girl (paidiske), probably the portress, to open the door, and the house was a meeting-place for the brethren, "many" of whom were praying there the night St. Peter arrived from prison (Acts 12:12-13).
The Encyclopedia of the Bible offers a similar explanation:
The name ̓Ιωάννης, is derived from the Heb. יﯴחָנָנ׃֙ or יהﯴחָנָ֥ן meaning “Yahweh is gracious” and points to his Jewish heritage. Μάρκος, on the other hand, is the common Gr. form of the Lat. Marcus and served as John’s “other name” (e.g. Acts 12:12). Other examples of Jews bearing Gr. (e.g. Acts 10:18) or Rom. (e.g. Acts 1:23) names in addition to their Heb. names are common in the NT and in some cases may indicate Rom. citizenship, in others perhaps a previous life of slavery to a Rom. family.
St. Mark appears to be among the many individuals in 1st-century Jerusalem to have two names in two different languages.
