After examining the pictures from Khew's and Gan's collection. I realised that the two Miletus does have some minor difference on the underside.

Miletus biggsii biggsii
- some pattern close to the sub-marginal spots on the forewing.
- one more obvious compared to 3.


Miletus symethus petronius
- pretty "clean" at the area next to the sub-marginal spots
- 3 "broken band" along the costa



Similiarities:
- both have a little dot near the base of hindwing/underside
- both have a row of dark tiny sub-marginal spots

Any comments?

PS: as such, I will relabel the Miletus spp. spotted in Chestnut Dr. (ie. +1!)