California Code, Elections Code - ELEC § 3014

(a) The elections official shall provide a replacement ballot to any voter upon receipt of a replacement ballot request from the voter.  Both of the following apply to a request made pursuant to this subdivision:

(b) The elections official shall provide a replacement ballot to the voter's representative upon receipt of a written request, on a form prescribed by the Secretary of State, signed by the voter under penalty of perjury, requesting that a ballot be provided to the voter's representative.  A ballot shall not be provided until both of the following occur:

(c) The voter shall mark the ballot, place it in the identification envelope, fill out and sign the identification envelope, and return the ballot pursuant to Section 3017.  These ballots shall be processed and counted in the same manner as other vote by mail ballots.

(d) The elections official shall keep a record of each vote by mail voter ballot sent to and received from a voter and shall verify, prior to counting any duplicate ballot, that the voter has not attempted to vote twice.  If it is determined that a voter has attempted to vote twice, both ballots shall be void.