If the voter marks more names than there are persons to be elected to an office, or if from the ballot it is impossible to determine the voter's choice for an office, his ballot shall not be counted for that office.
A.R.S. § 16-611
Certain defects invalidating vote for particular office
Official source: Arizona State Legislature. Reproduced from public-domain Arizona statutes; confirm against the official source for the current text. Not legal advice.