Hi all. A friend asked me a couple of questions regarding double-sided and checklist cards. I didn't want to give him misinformation, so I figured I'd ask here to verify. Thanks in advance!

1) A player must have the appropriate copies of double-sided cards to match his checklist cards in his deck, right? That is to say, it would be illegal to have a deck with four checklist cards representing Nissa, Vastwood Seer/Nissa, Sage Animist, but only one actual copy of the double-sided Nissa card, right?
2) At Competitive REL, would you be allowed to ask your opponent to present all copies of his double-faced cards for verification? Example: he has two checklist Nissas in his graveyard and one on the battlefield.

1) correct.
2) Not exactly, no - but each unique checklist card that's seen needs to correlate to a unique double-sided card.

Also, an oft-misunderstood requirement:

Originally posted by MTR 3.5:

If a player uses a checklist card to represent a double-faced card in his or her deck, then all of the double-faced cards in the deck must be represented by checklist cards

d:^D