Couldn't really tell from the pix if it's the SMA unit, no idea what the offset middle bolt does, could you check the underside to see if it attaches to the frame like the 2 original bolts?
Here's the installation instruction for the SMA unit and there's no mention of the offset hole, unless that extra bolt is to keep the hinge bracket (wedged from behind) from moving too much and causing misalignment of the swing arm? Pure speculation here. May be part of the STep #7?
http://smahummer.com/install_h2carrier.jsp