I have gifted b/g twins, 12 yo. Dd presented as gifted much earlier (for example, reading by her 2nd birthday, vs. 3.5yo for her brother) and more extremely, but both are stand outs in their grade at school (250 kids/grade). Neither is 2E now, but dd had an IEP for speech in 2nd-4th grade, and I feel confident we could get an ADHD diagnosis for ds if we pursued it. (We don't pursue it in part because his challenges with focus and organization are a source of stress only for parents and teachers, and not for him.)
When they were in 2nd grade, the school threw out the option of a full grade skip for dd, but we declined in part because of the twin factor.
We think having gifted twins is a wonderful thing - they've had in each other like-minded buddies since birth!