If a token is created as a copy of a legendary creature, do both die to the legend rule?

The legend rule (CR 704.5j) is a state-based action that checks whether a player controls two or more legendary permanents with the same name. If so, that player chooses one to keep and all others are put into their owner's graveyard. This applies to tokens just as much as to non-token permanents.

When a token is created as a copy of a legendary creature, it copies all the copiable values of that creature, including its name and legendary supertype (CR 706.2). The token is therefore also a legendary permanent with the same name as the original.

As soon as the token enters the battlefield, state-based actions are checked (CR 704.3). The controlling player now controls two legendary permanents sharing a name, so the legend rule triggers. That player must choose one to keep; the other — whether it's the original or the token — is immediately put into the graveyard. So in practice, you cannot simply 'double up' on a legendary creature this way.

Example: You control Emrakul, the Promised End. You use a spell to create a token that is a copy of it. State-based actions are checked: you now control two legendary permanents both named Emrakul, the Promised End. You choose one to keep; the other is put into the graveyard. You end up with exactly one Emrakul.

Note: if two different players each control a legendary permanent with the same name, the legend rule does not apply — it only checks permanents a single player controls (CR 704.5j).