Reply from Jason at Performance Nissan:

"just got off the phone with Nissan Motor Sports about the mounts. Some times when they make them they use the OEM mount and squeeze a harder bushing into them. So the mount will have the same number stamped into it but the insert is different."

I'm worried about that: the part # is on the urethane/poly, not the mount. So the mounts are 2 pieces? I'll keep you updated.