Same brand but switching flavors.

So to give Tessie a little more variety, is it OK to switch flavors of dry food? She is eating Blue Buff Wilderness Chicken and I was thinking of giving her Duck as well (Chicken in the morning and Duck at night). Would this be OK or would if screw up her stomach?
Thanks!

add the duck in slowly...

Not all cats can tolerate the Duck in foods. Agree with Sharky to do it slowly; but I would had a mix of the two - not separate feedings - just mix in the duck with the chicken so they are eating both flavors at the same time.

My vet recommends putting the two foods side by side but in separate bowls so you can see which one they are eating