A Notary Public must make sure that copies are true copies of the original documents after comparison. It may include marriage certificates, birth certificates, educational certificates. Most people require the certifying of true copies to be sent overseas.
To ensure the verification of original documents, visual comparisons must be conducted to ensure the copies of the original documents are authentic.
However, in this day and age of digital and/or softcopies of original documents, Notary Publics are called upon to think out of the box to certificate such copies, or copies of copies as true copies.