Yes but then they would have to be the same size and this can raise the ROF. I am more looking at longer lasting with same ROF or variable ROF. Also you couldnt remove one and lend it to someone in the field if there's died. As we know batteries sometimes die. And an extra gun on your team is always good.
but moreso i am looking for an external battery holder that dosnt look bad lol. We will look and see! Who knows maybe I can come up with a battery box that dosnt look horrible!