Another way to put this is that users think of some meetings as corporate bodies. Corporate bodies are typically agents. I read Rebecca Guenther's comment as more about how users would look for conference proceedings--as the product of a named corporate body--than about the catalog card format.
There is precedence for establishing two entity records for different aspects of the "same" thing. Parks are defined in LCSH as geographic entities. Some documents present the park name as an issuing body. In response, parallel authorities are created--the subject authority for the park as non-agent and a name authority for the park as agent, e.g., Everglades National Park (Fla.) and Everglades National Park (Agency : U.S.). But my sense has been that this was more about the organizational "division of the world" at LC and the differing conventions for access points in LCSH and LCNAF than about a conceptual division in the minds of users.