In determining valid signatures from voter registration records, the secretary may use the duplicate file of affidavits or may check the signatures against facsimiles of voter signatures, provided that the method of preparing and displaying the facsimiles complies with law.
Source:
Section 12815.8, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=PUC§ionNum=12815.8..