There may be certain types of documents where you will need multiple people to sign and approve the documents. In this type of situation you can use more than one digital signature on the same document. For example, a purchase requisition can require signatures from the person issuing the purchase requisition, as well as signatures from people, who have to approve the requisition.
How to Apply More Than One Digital Signature to a Document
When you need to have multiple digital signatures applied to a document, you will need to make sure everyone has their own digital signature. In addition, each person will also need a digital certificate containing the public key for every other person. The public key will be used to decrypt the document and allow them to open it. After it is opened, they can apply their own signature, using their own private key.