I am making a cake with raspberry filling and a whipped ganache filling. My question is, should I place the raspberry filling and whipped ganache filling, one on top of each other, or should I put the fillings in separate layers (separate each with a cake layer). I'm thinking if I put both, one on top of each other, without cake separating them, it might all mush together and taste and look weird?

If you have four layers, the center always looks nice with a different filling. But I do have several cakes that use IMBC as a filling with curd or jam on top. If they will stay separate, they can stack, or maybe a swirl of the two will work.