There has only been Rev. 2.0 8KHA+ boards made - every PCB containing the KT266A is identical in it's layout and has identical components.
Since the KT266A was a drop in replacement for the older KT266, the 1.3 might be a board printed for the older 8KHA KT266 and ended up having a KT266A chipset dropped in instead. This may have occurred on very early production runs. Some of the first sites to review these early boards had "8KHA" and "1.3" printed on them, when in fact it was really a mislabelled 8KHA+ Rev 2.0
I'd still double check it's not an 8KHA KT266 board; if it's not it's one of the small number of wrongly labelled KT266A boards kicking around.