If you copy a spell with cipher, can you encode the copy?
I don't believe so. The cipher spell is exiled then encoded. You can't exile the copy.
Ok so it's similar to tokens leaving the field?
When a copy resolves it disappears?
Cipher states you must exile the card, when you make a copy it is just a new spell on the stack not a card and as such it can not be ciphered.
702.98a Cipher appears on some instants and sorceries. It represents two abilities. The first is a spell ability that functions while the spell with cipher is on the stack. The second is a static ability that functions while the card with cipher is in the exile zone. "Cipher" means "If this spell is represented by a card, you may exile this card encoded on a creature you control" and "For as long as this card is encoded on that creature, that creature has 'Whenever this creature deals combat damage to a player, you may copy the encoded card and you may cast the copy without paying its mana cost.'"
Ok so it must be represented by a card. Got it. Thank!