Here is a demonstration of a PDF document that has a certifying signature plus four recipient signatures from four different certificate authorities that are part of Adobe’s Certified Document Services (CDS) program.
In v8 and higher, you will see a status bar across the top, indicating the valid document certification:
followed by the recipient signatures from each of the CAs:
For long term digital signature validation, each of these signatures also include an embedded OCSP response from the certificates in the chains and RFC3161 timestamps. This shows that the certificates were valid at the time of signing – even if the document is subsequently opened after certificate expiration or revocation.