wow thankyou all for your replies
I am really finding the "realistic frame of reference" such a helpful insight. One of my concerns has been whether to keep them in the same classroom or to separate them at some stage (there are no reasons to separate them at all--> they make individual friends, never fight and don't cheat/copy/trick)and this has certainly been insightful knowing that clustering them may have many benefits. At times I am concerned they are lumped together as a single entity (they look awfully alike and many of the specialist teachers who only see them once a week can't tell them apart and some children havent worked it out either despite being in their classroom all year!) but it is nice to know that clustering has benefits too. Our teacher has done some extension work this year (after some strong discussions from me) and we did have one episode where she set the benchmark too high and they both "failed" the task and I can see now that we possibly had no negative impact from that because both witnessed each other confused and perplexed and so didnt really care that they couldnt master it. I havent yet told our school the results but trying to muster the words for that discussion--> I think I need to sort out first how I see the future (things like same classroom v separate, same subject acceleration or different etc etc)
thanks again I'm sure I will have many more questions to follow as I try and sort through this.
