GaAs nano-mounds formed by droplet epitaxy are used as templates for growth of self-assembled InAs quantum dot clusters (QDCs). These QDCs are found to contain an average of thirteen dots per cluster, of which there are two families of different sized quantum dots. Excitation intensity-dependent photoluminescence (PL) demonstrates that there is no lateral coupling between the two different size quantum dots. Lateral transfer of carriers is observed between different size quantum dots due to thermal activation as seen in their different temperature-dependent optical behaviors.