Ok so reporting back for future reference on DXB-SIN-MEL. Deplaning seemed was at C23/C24, with passengers exiting the plane onto the arrivals level being the same level as the departures (unlike some airports where arrivals and departures are lead from/to separate levels), therefore it is possible to directly go to the Emirates lounge if arrivals was on time. There is no formal transit area for re-check in, keep the original boarding pass and in my case, was directed to go to gate C25/C26 right next door for security check, which seemed was at the end of the terminal and therefore easy to be cordoned off for the usual x-ray and passport check.