There doesn't seem to be any SLI profile for the beta, which indicates that the final game won’t support multiple GPUs- then again, this could be an issue restricted to just the beta. The full changelog follows:

This is GeForce Hot Fix driver version 364.96 that addresses the following:

Support for DOOM Open Beta
Known issues:

GFE may show the following error if launched without a network connection: “GeForce Experience encountered an error and must close”