While both our dds present as gifted in many ways, their interests, personalities, and styles are very different from each other. Our oldest was very ahead academically by the time she started K, and our younger one, in K this year is not.
We had both girls tested and in paper they are not that different. Their verbal IQs are similar and the oldest has higher performance /non-verbal.
I think it was important that we got a sense of our youngest. We will not be surprised if academically she takes off suddenly. OTOH, if she does not, given her IQ we would investigate possible 2E issues.