It seems like you may have file sharing turned on, so Time Machine is seeing the disk twice: once attached to your computer, and once when it searches for file servers (it will find a file server even if that file server just so happens to be on the same computer as Time Machine is on). If you remove it from the local pool and add it from the file server pool, it will do the backup over the network rather than directly...which, yes, means your computer would be talking to itself on the network.
SRP is Secure Remote Password protocol. I believe AUTH is Apple's Time Machine over AFP thing, though I'm not sure about that.
