The Apostle John always uses the Greek "amen" or "αμήν", at the start of a statement twice and never once and only for what Jesus says. Others use the word once and never twice (at the start of a statement).
The letters of 1 and 2 John use the "amen" once (at the end of the letter). 3 John does not use "amen". John uses "amen" in the book of John only once and that is at the very end of the book.
Sometime between about 500 AD and 1500 AD, the "
amen" at the start of a verse started to be translated as "
truly" or, from the Latin, "
verily". So the "
amen, amen" became "
verily, verily".
Here are the
25 times in John where the word "
verily" is used twice (and never once).
KJV: Jesus answered them and said, Verily, verily, I say unto you, Ye seek me, not because ye saw the miracles, but because ye did eat of the loaves, and were filled.
Greek: απεκριθη αυτοις ο ιησους και ειπεν αμην αμην λεγω υμιν ζητειτε με ουχ οτι ειδετε σημεια αλλ οτι εφαγετε εκ των αρτων και εχορτασθητε
KJV: Verily, verily, I say unto thee, When thou wast young, thou girdedst thyself, and walkedst whither thou wouldest: but when thou shalt be old, thou shalt stretch forth thy hands, and another shall gird thee, and carry thee whither thou wouldest not.
Greek: αμην αμην λεγω σοι οτε ης νεωτερος εζωννυες σεαυτον και περιεπατεις οπου ηθελες οταν δε γηρασης εκτενεις τας χειρας σου και αλλος σε ζωσει σε και οισει οπου ου θελεις