You need to know the butterfly venations & the terms used to describe the spots otherwise what I say may make no sense.
'Overlap' mean to cover partially or wholly their facing margins.
In P. mingo spot 4 & 5 overlap the other spots ie spot 5 overlap spot 6 ( not always), & spot 4 overlaps spot 3.
In P. trachala spots 4 & 5 do not overlap the other spots. POTANTHUS.png