In general, you definitely don't want to be going into the muck except under very, very exceptional circumstances. The muck is the muck.
However, this may be one of those rare circumstances. You say that "First guy showed his hand and the second guy as well". The rules are clear:
10. Killing Winning Hand Dealers cannot kill a winning hand that was tabled and was obviously the winning hand. Players are encouraged to assist in reading tabled hands if it appears that an error is about to be made.
Whenever all hands have been duly tabled, we want the best hand win to the pot. I believe a TD must do whatever is possible to achieve this, in the best interests of the tournament. Also, a player, by tabling his hand, is afforded a certain degree of protection that he would not otherwise be entitled to if his hand were mucked without being tabled for whatever reason. Just to be clear, the only reason I am going into the muck here is that both hands have been properly tabled.
Are you saying that no one at the table saw the second hand at all? The dealer? The other players? (I'm assuming no cameras)? What did the player say he had? Even if the second player could not remember the exact suits, he probably at least knows the ranks and the colors, and I don't have a problem looking into the muck to investigate... it will likely only be a problem if the suits actually make a difference as to who wins the hand and if there are actually two cards of the same color and the same rank in the muck.