Does 'shuffle your library' mandate that the cards actually change order?
As Jefromi points out, the deck is not left in a randomised state unless there's only one of the card being removed in it.

Now, you could pick one of the matching cards at random, but that becomes complicated and error prone. (What if there are three matching card, but the 3rd party only sees two?) I would not accept this.

Original post follows.



In what circumstance would there be a neutral 3rd party handling your deck? But ok, let's assume that's somehow the case. From the tournament rules:


  Randomization is defined as bringing the deck to a state where no player can have any information regarding the order or position of cards in any portion of the deck.


So technically, it is randomised. I'm assuming you okayed it with your opponent, otherwise, the following could apply:


  If the opponent does not believe the player made a reasonable effort to randomize his or her deck, the opponent must notify a judge.


That said, (emphasis mine)


  At Competitive and Professional REL tournaments, players are required to shuffle their opponents’ decks after their owners have shuffled them. The Head Judge can require this at Regular REL tournaments as well.


Given this, a judge may insist you are also required to actually shuffle the deck. Why don't you ask your judge since it really comes down to what he thinks.

Quotes come from the Tournament Rules. They apply to Competitive and Pro REL, but that's the only place your question really matters.