Is drinking different flavors of the same drink bad for me?

So my roommate and i got 2 6-packs of smirnoff ice, one grape and one red-white-and-berry. I like to drink one and then another instead of drinking all 3 of one flavor and then all 3 of another. He said that that is bad for me and its like mixing liquor or some shit. But that just doesnt make sense to me and i feel like its not true but figured yall may know?