Cleanly open the tops of the 2 coconuts. Pour out the coconut juice and reserve.
Mix the duck eggs, white sugar, palm sugar and salt together. Crush and mix the pandan leaves in this mixture until the sugar has dissolved. Add the coconut juice and mix well.
Strain the egg mixture through cheesecloth and discard the pandan leaves. Fill the coconuts with the egg mixture.
Place the filled coconuts in a prepared steamer and steam for 30 minutes.