I hope others will add their two cents to this post, it 's a good one, thank you.
When we raise babies,to 16 plus weeks old, we have to be careful about bonding with them, this is hard, you love each one of them, but you don't want them to love you to much in return, so it will be easier for them to move on to new life family's. As siblings they teach each other, and part of their training is playing, feeding and socializing with each other,and you can tell, at a certain point they start bonding with each other, at this time you serparate them, and you have to spend less time with them, hopping that soon they'll move on to their new home...It's hard..
This point might be close for your 2 babies, from what you say. If the 2 bond with each other, they'll bond less and less with you, [99% of the time]
If separated for a longer length of time, they'll be able to bond with the 2 of you, and be part of the flock with each other....Jayd