The notary could be verifying one of the signers, but there might be some question as to his competence if he verified both. The only responsibility of the notary is to verify that the identification of the person signing matches the name on the document. If he was only verifying one of the signatures, he/she might have been ok. There are some specific requirements regarding the limits and responsibilities of a notary. * Not necessarily. It depends on what the document was and who the signers were. For example if the signers were husband and wife and they resided in a community property state the validation would be legally acceptable.