Where is WF Notification "Responder" data stored (when a user acting as a Proxy approves)?

Hi Community,

Does anyone know where the "Responder" data is stored in relation to Workflow notifications when a proxy user has approved on behalf of the original recipient? 

To clarify what I'm referring to as "proxy user", when a WF notification goes to user "Approver1," but they are out of the office and did not set up vacation rules, if I (user BAUGH) am set up as an authorized proxy for "Approver1," I can go and approve the transaction on their behalf.

Below is an example screenshot of an approved WF Notification, you can see that the "Responder" (BAUGH) is different from the notification's original recipient (Approver1).