Based on C&P4's and Fleming's records, the following species are/were found in Singapore :

Potanthus trachala tytleri
Potanthus juno juno
Potanthus omaha omaha Lesser Dart
Potanthus confucius dushta
Potanthus hetaerus serina

Oriens gola pseudolus

Telicota besta bina
Telicota colon stinga
Telicota augias augias

So, in the ID'ing of these lookalikes, do familiarise yourselves with the appearances and characteristics of these species first (from C&P4). Chances are that they do exist, but not positively ID'ed yet.

Reference : Page 433 of C&P4 and Fleming