@chunsiong.zoom, thank you for letting me know the unsuported aspect of the solution.
I could find here in devforum other users who have required running more than one client at the same time: @liminal_andy and @fboncini. Do you still need this, Andy and Fernando?
Their SDKERR_WRONG_USEAGE when Join multiple meetings post must have been the source reference for our implementation.
JFYI, we found that sdkPathPostfix keeps working as expected but, in v5.16.x, having a distinct sdkPath folder is not sufficient anymore for being able to run a second SDK instance.