Chrome Version: 65.0.3285.0
OS: iOS

What steps will reproduce the problem?
(1) Remove existing payment methods from https://payments.google.com/
(2) Remove existing addresses from autofill settings. 
(3) Add a new payment method in https://payments.google.com/
(4) Wait until the card and its billing address are available in autofill settings.
(5) Toggle the switch to sync server cards/addresses

A duplicate address is now available.