Is it bad to mix 2 different kibbles?

I have a fussy cat and I just got 2 dry foods yesterday that she actually ate. It's Royal Canin Indoor Beauty 35 and Chicken Soup for the Pet Lover's Soul Indoor Hairball. (They didn't have the regular Chicken soup at the store and I wanted to try the brand.) Is it ok to mix kibbles or can you create some kind of imbalance? She gets wet food every day too. 

I mix several types for my fussy eater. Otherwise he would start to turn his nose up at it!
The only concern I have about doing this is if one of the kibble made him sick or something, then I wouldn't know which one. This is why I only mix up a week's worth at a time and keep the remainder in their separate bags. You can see which kibble is which that way.

I'd definitely keep the actual food bags separately. I'd just mix them in her bowl.