One of the two grows slow, should I replace her? I have a northern light auto and White Widow auto, dont know which is which :/

One of my girls grows very slow. (see pics). She looks healthy but like I said.. I had problem with heat, was 30 degrees daytemp the last few days. Other than that it's all fine. I spray them often and they have good lights. The other one receives the same care and grows well.