Late 2005 G5 are dual cores not dual processors. They came in three variants, 2.0 DC, 2.3 DC and 2x.2.5DC (quad core).
There is no dual processor 2.3GHz late 2005 PMG5.
If you have PCIe graphics then it is a late 2005 G5. Early models of G5's have AGP graphics. You can tell a late 2005 PMG5 by looking at the back. If there is a white strip (Wifi Antennae), then it is a late 2005 if there is none, it is an early PMG5.