A digital signature (not to be confused with a digital certificate) is an electronic signature that is used to authenticate the identity of a message sender or document signer, and usually to ensure that the original message/document content is unchanged (document integrity).
What the advantage of sequentialy signing a document? That means signing a document by two people in a sequential manner?
In another question's answer, D.W. wrote: Make sure there is authenticity protection for the encrypted data (e.g., encrypt and then sign/MAC): you will need both confidentiality and authenticity ...
Suppose I have an Infopath form that is digitally signed today by a valid, and active user. When that user leaves the company, we disable the account and revoke the certificate. This causes a problem ...