When the oral tradition which G-d gave to Moses, was taught to the elders of each tribe, there were always two witnesses present, to make sure the oral tradition was give down without error, so why wasn't there two witnesses to hear the prophets words, when the prophets received their prophecy from G-d, so as to make sure the prophecy was written down without error
If a navi is kovesh ne'vu'aso he is chaya misah, the question is how do we know he is being kovesh ne'vuaso?
The mephorshim explain that every navi heard every nevuah, just that only one was meant to transmit the message.
Therefore when the prophecy was transcribed other neviim would be able to verify its accuracy.
This would not apply to Moshe who had unique nevuah.