If the First Bukhari was authentic and accurate, 'Saheeh Bukhari' would have not compiled.
Same in the case of Muslim. If the First Muslim was authentic and accurate, 'Saheeh Muslim' would have not compiled.
"For, One Day, We shall raise from every community a leading witness against them from among themselves. And We shall call you (O Prophet) to testify regarding those whom your message has reached. The Book We have revealed to you explains everything; a Guide and Grace and the glad tiding for Muslims. (16:89)"