In John 18:37, Pilate asks Jesus whether he is a king, and Jesus confirms the fact:
YLT: Pilate, therefore, said to him, 'Art thou then a king?' Jesus answered, 'Thou dost say it; because a king I am, I for this have been born, and for this I have come to the world, that I may testify to the truth; every one who is of the truth, doth hear my voice.'
ASV: Pilate therefore said unto him, Art thou a king then? Jesus answered, Thou sayest that I am a king. To this end have I been born, and to this end am I come into the world, that I should bear witness unto the truth. Every one that is of the truth heareth my voice.
KJV: Pilate therefore said unto him, Art thou a king then? Jesus answered, Thou sayest that I am a king. To this end was I born, and for this cause came I into the world, that I should bear witness unto the truth. Every one that is of the truth heareth my voice.
The NKJV even supplies "rightly" to make the confirmation more explicit.
NKJV: Pilate therefore said to Him, “Are You a king then?” Jesus answered, “You say rightly that I am a king. For this cause I was born, and for this cause I have come into the world, that I should bear witness to the truth. Everyone who is of the truth hears My voice.”
Yet some versions translate a completely opposite meaning, with Jesus appearing to deny what Pilate said:
NLT: Pilate said, “So you are a king?” Jesus responded, “You say I am a king. Actually, I was born and came into the world to testify to the truth. All who love the truth recognize that what I say is true.”
NIV: “You are a king, then!” said Pilate. Jesus answered, “You say that I am a king. In fact, the reason I was born and came into the world is to testify to the truth. Everyone on the side of truth listens to me.”
Interestingly, unlike in many other cases, these translations don't supply footnotes indicating any alternative meanings.
What is the cause of these contradictory interpretations?

