Complex sentence: An electoral roll has a number of function, including to streamline voting on election day, and to combat electoral fraud by enabling authorities to verify the identity and entitlement to a vote of applicants, such as ensuring a person doesn't vote multiple times.
Split into simpler sentences: An electoral roll has a number of functions, especially to streamline voting on election day. Voter registration is also used to combat electoral fraud by enabling authorities to verify an applicant's identity and entitlement to a vote, and to ensure a person doesn't vote multiple times.