Why does the KJV not include the phrase "having his name" in Revelation 14:1?

Question

King James Version

14:1 And I looked, and, lo, a Lamb stood on the mount Sion, and with him an hundred forty [and] four thousand, having his Father's name written in their foreheads.

American Standard Version

14:1 And I saw, and behold, the Lamb standing on the mount Zion, and with him a hundred and forty and four thousand, having his name, and the name of his Father, written on their foreheads.

Darby's English Translation

14:1 And I saw, and behold, the Lamb standing upon mount Zion, and with him a hundred and forty-four thousand, having his name and the name of his Father written upon their foreheads

Revelation 14:1 NASB

[1]Then I looked, and behold, the Lamb was standing on Mount Zion, and with Him one hundred and forty-four thousand, having His name and the name of His Father written on their foreheads.

Why does the KJV not include this phrase?

Answer 1

The translators of the KJV used a Greek text -- the "Received Text (RT)" -- that was based on late medieval manuscripts.

In Revelation 14:1, those manuscripts omitted the phrase τὸ ὄνομα αὐτοῦ καὶ, and so gave a shorter version of the verse, as OP notes. At the text link, compare especially "Stephanus Textus Receptus 1550" and "Scrivener's Textus Receptus 1894" which have the shorter text, against the others which have the fuller text.

Interestingly, the critical Nestle Aland NT Greek text does not even record variants for this textual situation. This is the manuscript evidence, as recorded by the Center for NT Textual Studies:

Note that only "1773" (a manuscript number) and "TR" (the Textus Receptus = RT) have this omission (OM).

This has been understood as an obvious scribal mistake. In the string:

τὸ ὄνομα αὐτοῦ καὶ τὸ ὄνομα τοῦ πατρὸς αὐτοῦ

the scribe's eye has jumped from the first τὸ ὄνομα to the second, thus leaving the shorter text used by the KJV translators, but not in more recent translations based on a wider (and often older) mansuscript base.