Nothing to worry about, here. It's just two plants distinguishing themselves from one another.
Cannabis plants have phenotypes. This means they each have slightly different genes, even though they have the same parents. A lot like humans. Take a brother and sister from the same parents and you'll see that they have different genetics, despite being from the same bloodline. Different eyes, hairline, height, build, etc.
Well, cannabis plants are the same way. Phenotype hunting is actually the funnest part of growing for me. I like to pop a bunch of seeds, clone them, then put the clones into flower. If i like the genetics of one of the seeds enough, i'll keep it as a mother plant to do future runs with it. If i don't like it that much, i just stick the mother plant into flower and don't keep it around.
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I hope this helps!