This solution explains the repercussions of updating all addresses with AddressFinder rather than just only addresses changed with NCOA.
To add this information onto all records submitted to AddressFinder, you must leave the checkbox for "Update Only NCOA Addresses" unmarked on the General tab for the update. When doing this, any of the options that you select for the update will also be applied to these records. So, if you select to add an Info Source to the records, all of them, including the ones that were not actually updated but standardized will have this new Info Source. If you choose to save the old addresses, a copy of the current address will be saved, and the new address will be put in its place, so some of the records will have duplicate addresses.
To avoid the duplicate addresses, you can run the AddressFinder update once, selecting to only update NCOA changes and save your old addresses, then run it again, not selecting either option.